Systems and methods for mixing exhaust gases and reductant in an aftertreatment system

ABSTRACT

A multi-stage mixer includes a multi-stage mixer inlet, a multi-stage mixer outlet, a first flow device, and a second flow device. The multi-stage mixer inlet is configured to receive exhaust gas. The multi-stage mixer outlet is configured to provide the exhaust gas to a catalyst. The first flow device is configured to receive the exhaust gas from the multi-stage mixer inlet and to receive reductant such that the reductant is partially mixed with the exhaust gas within the first flow device. The first flow device includes a plurality of main vanes and a plurality of main vane apertures. The plurality of main vane apertures is interspaced between the plurality of main vanes. The plurality of main vane apertures is configured to receive the exhaust gas and to cooperate with the plurality of main vanes to provide the exhaust gas from the first flow device with a swirl flow.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present application claims the benefit of, and priority to, U.S.Provisional Patent Application No. 62/515,743, filed Jun. 6, 2017, thecontents of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present application relates generally to the field of aftertreatmentsystems for internal combustion engines.

BACKGROUND

For internal combustion engines, such as diesel engines, nitrogen oxide(NO_(x)) compounds may be emitted in the exhaust. To reduce NO_(x)emissions, a selective catalytic reduction (SCR) process may beimplemented to convert the NO_(x) compounds into more neutral compounds,such as diatomic nitrogen or water, with the aid of a catalyst and areductant. The catalyst may be included in a catalyst chamber of anexhaust system, such as that of a vehicle or power generation unit. Areductant, such as anhydrous ammonia, aqueous ammonia, diesel exhaustfluid (DEF), or aqueous urea, is typically introduced into the exhaustgas flow prior to the catalyst chamber. To introduce the reductant intothe exhaust gas flow for the SCR process, an SCR system may dose orotherwise introduce the reductant through a dosing module that vaporizesor sprays the reductant into an exhaust pipe of the exhaust systemup-stream of the catalyst chamber. The SCR system may include one ormore sensors to monitor conditions within the exhaust system.

SUMMARY

In an embodiment, a multi-stage mixer includes a multi-stage mixerinlet, a multi-stage mixer outlet, a first flow device, and a secondflow device. The multi-stage mixer inlet is configured to receiveexhaust gas. The multi-stage mixer outlet is configured to provide theexhaust gas to a catalyst. The first flow device is configured toreceive the exhaust gas from the multi-stage mixer inlet and to receivereductant such that the reductant is partially mixed with the exhaustgas within the first flow device. The first flow device includes aplurality of main vanes and a plurality of main vane apertures. Theplurality of main vane apertures is interspaced between the plurality ofmain vanes. The plurality of main vane apertures is configured toreceive the exhaust gas and to cooperate with the plurality of mainvanes to provide the exhaust gas from the first flow device with a swirlflow that facilitates mixing of the reductant and the exhaust gas. Thesecond flow device is configured to receive the exhaust gas and thereductant from the first flow device. The second flow device includes aplurality of second flow device apertures configured to provide theexhaust gas and the reductant from the second flow device to thecatalyst via the multi-stage mixer outlet.

In another embodiment, a multi-stage mixer includes a multi-stage mixerinlet, a multi-stage mixer outlet, and a first flow device. Themulti-stage mixer inlet is configured to receive exhaust gas. Themulti-stage mixer outlet is configured to provide the exhaust gas to acatalyst. The first flow device is configured to receive the exhaust gasfrom the multi-stage mixer inlet and configured to receive reductantsuch that the reductant is partially mixed with the exhaust gas withinthe first flow device. The first flow device includes a Venturi body, aplurality of main vanes, a plurality of main vane apertures, a pluralityof auxiliary vanes, and a plurality of auxiliary vane apertures. TheVenturi body is defined by a body inlet proximate the multi-stage mixerinlet and a body outlet proximate the multi-stage mixer outlet. Theplurality of main vanes is positioned within the Venturi body andproximate the body outlet. The plurality of main vane apertures isinterspaced between the plurality of main vanes. The plurality of mainvane apertures is configured to receive the exhaust gas and cooperatewith the plurality of main vanes to provide the exhaust gas from thefirst flow device with a swirl flow that facilitates mixing of thereductant and the exhaust gas. The plurality of auxiliary vanes ispositioned within the Venturi body and proximate the body inlet. Theplurality of auxiliary vane apertures is interspaced between theplurality of auxiliary vanes. The plurality of auxiliary vane aperturesis configured to receive the exhaust gas and cooperate with theplurality of auxiliary vanes to provide the exhaust gas into the Venturibody with a swirl flow that facilitates mixing of the reductant and theexhaust gas.

In yet another embodiment, a multi-stage mixer includes a multi-stagemixer inlet, a multi-stage mixer outlet, and a first flow device. Themulti-stage mixer inlet is configured to receive exhaust gas. Themulti-stage mixer outlet is configured to provide the exhaust gas to acatalyst. The first flow device is configured to receive the exhaust gasfrom the multi-stage mixer inlet and receive reductant such that thereductant is partially mixed with the exhaust gas within the first flowdevice. The first flow device includes a Venturi body, a plurality ofmain vanes, a plurality of main vane apertures, and an exhaust gasguide. The Venturi body is defined by a body inlet proximate themulti-stage mixer inlet and a body outlet proximate the multi-stagemixer outlet. The Venturi body includes an exhaust gas guide aperturedisposed along the Venturi body between the body inlet and the bodyoutlet. The plurality of main vanes is positioned within the Venturibody and proximate the body outlet. The plurality of main vane aperturesis interspaced between the plurality of main vanes. The plurality ofmain vane apertures is configured to receive the exhaust gas andcooperate with the plurality of main vanes to provide the exhaust gasfrom the first flow device with a swirl flow that facilitates mixing ofthe reductant and the exhaust gas. The exhaust gas guide is coupled tothe Venturi body about the exhaust gas guide aperture. The exhaust gasguide is configured to separately receive exhaust gas and reductant fromoutside of the Venturi body, mix the exhaust gas and reductant receivedfrom outside of the Venturi body in the exhaust gas guide, and providethe mixed exhaust gas and reductant into the Venturi body.

In yet another embodiment, a multi-stage mixer includes a multi-stagemixer inlet, a multi-stage mixer outlet, and a first flow device. Themulti-stage mixer inlet is configured to receive exhaust gas. Themulti-stage mixer outlet is configured to provide the exhaust gas to acatalyst. The first flow device is configured to receive the exhaust gasfrom the multi-stage mixer inlet and receive reductant such that thereductant is partially mixed with the exhaust gas within the first flowdevice. The first flow device includes a Venturi body, a plurality ofconduit straight vanes, and an exhaust gas guide. The Venturi body isdefined by a body inlet proximate the multi-stage mixer inlet and a bodyoutlet proximate the multi-stage mixer outlet. The Venturi body includesan exhaust gas guide aperture disposed along the Venturi body betweenthe body inlet and the body outlet. The plurality of conduit straightvanes is positioned within the Venturi body and proximate the bodyoutlet. The plurality of conduit straight vanes is configured tointerface with the exhaust gas and provide the exhaust gas from thefirst flow device with a swirl flow that facilitates mixing of thereductant and the exhaust gas. The exhaust gas guide is coupled to theVenturi body about the exhaust gas guide aperture. The exhaust gas guideis configured to separately receive exhaust gas and reductant fromoutside of the Venturi body, mix the exhaust gas and reductant receivedfrom outside of the Venturi body in the exhaust gas guide, and providethe mixed exhaust gas and reductant into the Venturi body.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features,aspects, and advantages of the disclosure will become apparent from thedescription, the drawings, and the claims, in which:

FIG. 1 is a block schematic diagram of an example selective catalyticreduction system having an example reductant delivery system for anexhaust system;

FIG. 2 is a cross-sectional view of an example multi-stage mixer;

FIG. 3 is a cross-sectional view of another multi-stage mixer;

FIG. 4 is a cross-sectional view of yet another multi-stage mixer;

FIG. 5 is a cross-sectional view of yet another multi-stage mixer;

FIG. 6A is a cross-sectional view of yet another multi-stage mixer;

FIG. 6B is front view of a flow device for the multi-stage mixer shownin FIG. 6A;

FIG. 6C is a front view of another flow device for the multi-stage mixershown in FIG. 6A;

FIG. 7 is a representation of velocity flow lines of exhaust gaseswithin a multi-stage mixer;

FIG. 8 is a representation of a reductant droplet distribution within amulti-stage mixer;

FIG. 9A is a front view of an example flow device for a multi-stagemixer;

FIG. 9B is a front view of another flow device for a multi-stage mixer;

FIG. 9C is a front view of another flow device for a multi-stage mixer;

FIG. 9D is a front view of another flow device for a multi-stage mixer;

FIG. 9E is a front view of another flow device for a multi-stage mixer;

FIG. 9F is a front view of another flow device for a multi-stage mixer;

FIG. 9G is a front view of another flow device for a multi-stage mixer;

FIG. 10A is a cross-sectional view of an exhaust gas guide and areductant guide for a multi-stage mixer;

FIG. 10B is a cross-sectional view of another exhaust gas guide and areductant guide for a multi-stage mixer;

FIG. 10C is a cross-sectional view of yet another exhaust gas guide fora multi-stage mixer;

FIG. 10D is a cross-sectional view of yet another exhaust gas guide fora multi-stage mixer;

FIG. 11A is a front view of yet another flow device for a multi-stagemixer;

FIG. 11B is a front view of yet another flow device for a multi-stagemixer;

FIG. 11C is a front view of yet another flow device for a multi-stagemixer;

FIG. 11D is a front view of yet another flow device for a multi-stagemixer;

FIG. 11E is a cross-sectional view of yet another multi-stage mixer;

FIG. 12A is a cross-sectional view of yet another multi-stage mixer;

FIG. 12B is a cross-sectional view of yet another multi-stage mixer;

FIG. 13 is a cross-sectional view of yet another multi-stage mixer;

FIG. 14 is a cross-sectional view of yet another multi-stage mixer;

FIG. 15 is a cross-sectional view of yet another multi-stage mixer;

FIG. 16 is front view of a mixer for a multi-stage mixer;

FIG. 17 is a cross-sectional view of yet another multi-stage mixer;

FIG. 18A is a front view of another mixer for a multi-stage mixer;

FIG. 18B is a front view of another mixer for a multi-stage mixer;

FIG. 18C is a front view of another mixer for a multi-stage mixer;

FIG. 19 is a cross-sectional view of yet another multi-stage mixer;

FIG. 20 is a view of a downstream face of a multi-stage mixer;

FIG. 21 is a view of an upstream face of a multi-stage mixer;

FIG. 22A is side view of yet another mixer for a multi-stage mixer;

FIG. 22B is another side view the mixer shown in FIG. 22A;

FIG. 23 is bottom perspective view of yet another mixer for amulti-stage mixer;

FIG. 24 is side view of a portion of the mixer shown in FIG. 23;

FIG. 25 is side view of a central hub for a multi-stage mixer;

FIG. 26 is side view of the central hub shown in FIG. 25 with aplurality of vanes;

FIG. 27 is rear view of yet another flow device for a multi-stage mixer;

FIG. 28 is rear view of yet another flow device for a multi-stage mixer;

FIG. 29 is a plot for analyzing the normalized pressure drop and/oruniformity index associated with a flow device for a multi-stage mixer;

FIG. 30 is rear view of yet another flow device for a multi-stage mixer;

FIG. 31 is top perspective view of yet another mixer for a multi-stagemixer;

FIG. 32 is side cross-sectional view of the mixer shown in FIG. 31; and

FIG. 33 is side cross-sectional view of a multi-stage mixer includingthe mixer shown in FIG. 31.

It will be recognized that some or all of the figures are schematicrepresentations for purposes of illustration. The figures are providedfor the purpose of illustrating one or more implementations with theexplicit understanding that they will not be used to limit the scope orthe meaning of the claims.

DETAILED DESCRIPTION

Following below are more detailed descriptions of various conceptsrelated to, and implementations of, methods, apparatuses, and systemsfor flow distribution in an aftertreatment system. The various conceptsintroduced above and discussed in greater detail below may beimplemented in any of numerous ways, as the described concepts are notlimited to any particular manner of implementation. Examples of specificimplementations and applications are provided primarily for illustrativepurposes.

I. OVERVIEW

Internal combustion engines (e.g., diesel internal combustion engines,etc.) produce exhaust gases that are often treated within anaftertreatment system. This treatment often includes passing the exhaustgases through a catalyst. By providing the catalyst with a uniform flowof the exhaust gases, the efficiency of the catalyst, and therefore ofthe aftertreatment system, may be increased. Various components, such asbaffles, may be included within an aftertreatment system to change theflow of the exhaust gases into the catalyst. Conventional aftertreatmentsystems implement components that are difficult to scale (e.g., fordifferent applications, etc.) in a radial direction (e.g., variousdiameters, etc.) and in an axial direction (e.g., various lengths,various numbers of components, various configurations of components,etc.). For example, baffles may have complicated shapes that requireadvanced manufacturing techniques, and therefore substantial cost, toproduce. As a result, conventional aftertreatment systems do not offerthe flexibility necessary to be easily implemented in applications withvarying engine ratings and/or operating conditions. Further,conventional aftertreatment systems typically utilize complicatedcomponents that are expensive and require difficult and time intensivemanufacturing.

Implementations described herein relate to a multi-stage mixer thatincludes a plurality of flow devices that cooperate to provide acatalyst with a substantially uniform flow of exhaust gases andreductant, facilitate substantially uniform reductant distribution inthe exhaust gases downstream of the multi-stage mixer, and provide arelatively low pressure drop (e.g., the pressure of the exhaust gases atthe inlet of the multi-stage mixer less the pressure of the exhaustgases at the outlet of the multi-stage mixer, etc.), all in a relativelycompact space, compared to conventional aftertreatment systems. The flowdevices are mostly symmetrical and relatively easy to manufacturecompared to the complicated devices currently used in aftertreatmentsystems. As a result, the multi-stage mixer can be easily and readilyscaled for various applications while consuming less physical space thandevices currently used in aftertreatment systems. The multi-stage mixermay be configured to dose the exhaust gases with reductant, to cause aninternal swirl flow that mixes the reductant within the exhaust gases,and to create a uniform dispersion of the reductant within the uniformflow of the exhaust gases that flows into the catalyst. The multi-stagemixer may minimize spray impingement on wall surfaces due to swirl flowand relatively high shear stresses produced by the multi-stage mixer,thereby mitigating deposit formation and accumulation within themulti-stage mixer and associated exhaust components.

In some implementations, the multi-stage mixer includes an exhaust gasguide that directs exhaust gases towards reductant ejected from areductant guide. The exhaust gases flow into the exhaust gas guide viaapertures that are disposed on at least part of the exhaust gas guide.The exhaust gases then assist the reductant in traveling into a flowdevice whereby the reductant and the exhaust gases may be subsequentlymixed via a swirl flow. The mixing may improve decomposition byutilizing the low pressure created by swirl flow and/or Venturi flow,enhance ordinary and turbulent diffusion, and elongate a mixingtrajectory of the exhaust gases and the reductant. Swirl flow refers toflow that swirls about a center axis of the multi-stage mixer and/or acenter axis of a flow device. Venturi flow refers to flow which occursdue to a low pressure region resulting from a reduction ofcross-sectional area and a local flow acceleration.

In some implementations, a flow device of the multi-stage mixer includesinternal plates that are positioned under the reductant guide. As thereductant flows into the flow device, the reductant contacts theinternal plates which facilitate mixing of the reductant within theexhaust gases by reducing the Stokes number of the reductant (e.g.,reductant droplets, etc.) via splashing.

II. OVERVIEW OF AFTERTREATMENT SYSTEM

FIG. 1 depicts an aftertreatment system 100 having an example reductantdelivery system 110 for an exhaust system 190. The aftertreatment system100 includes a particulate filter, for example a diesel particulatefilter (DPF) 102, the reductant delivery system 110, a decompositionchamber or reactor 104, a SCR catalyst 106, and a sensor 150. In someembodiments, the SCR catalyst 106 includes an ammonia oxidation catalyst(ASC).

The DPF 102 is configured to remove particulate matter, such as soot,from exhaust gas flowing in the exhaust system 190. The DPF 102 includesan inlet, where the exhaust gas is received, and an outlet, where theexhaust gas exits after having particulate matter substantially filteredfrom the exhaust gas and/or converting the particulate matter intocarbon dioxide. In some implementations, the DPF 102 may be omitted.

The decomposition chamber 104 is configured to convert a reductant, suchas urea or DEF, into ammonia. The decomposition chamber 104 includes areductant delivery system 110 having a doser or dosing module 112configured to dose the reductant into the decomposition chamber 104 (forexample, via an injector such as the injector described below). In someimplementations, the reductant is injected upstream of the SCR catalyst106. The reductant droplets then undergo the processes of evaporation,thermolysis, and hydrolysis to form gaseous ammonia within the exhaustsystem 190. The decomposition chamber 104 includes an inlet in fluidcommunication with the DPF 102 to receive the exhaust gas containingNO_(x) emissions and an outlet for the exhaust gas, NO_(x) emissions,ammonia, and/or reductant to flow to the SCR catalyst 106.

The decomposition chamber 104 includes the dosing module 112 mounted tothe decomposition chamber 104 such that the dosing module 112 may dosethe reductant into the exhaust gases flowing in the exhaust system 190.The dosing module 112 may include an insulator 114 interposed between aportion of the dosing module 112 and the portion of the decompositionchamber 104 on which the dosing module 112 is mounted. The dosing module112 is fluidly coupled to one or more reductant sources 116. In someimplementations, a pump 118 may be used to pressurize the reductant fromthe reductant sources 116 for delivery to the dosing module 112.

The dosing module 112 and pump 118 are also electrically orcommunicatively coupled to a controller 120. The controller 120 isconfigured to control the dosing module 112 to dose reductant into thedecomposition chamber 104. The controller 120 may also be configured tocontrol the pump 118. The controller 120 may include a microprocessor,an application-specific integrated circuit (ASIC), a field-programmablegate array (FPGA), etc., or combinations thereof. The controller 120 mayinclude memory, which may include, but is not limited to, electronic,optical, magnetic, or any other storage or transmission device capableof providing a processor, ASIC, FPGA, etc. with program instructions.The memory may include a memory chip, Electrically Erasable ProgrammableRead-Only Memory (EEPROM), Erasable Programmable Read Only Memory(EPROM), flash memory, or any other suitable memory from which thecontroller 120 can read instructions. The instructions may include codefrom any suitable programming language.

The SCR catalyst 106 is configured to assist in the reduction of NO_(x)emissions by accelerating a NO_(x) reduction process between the ammoniaand the NO_(x) of the exhaust gas into diatomic nitrogen and water. TheSCR catalyst 106 includes an inlet in fluid communication with thedecomposition chamber 104 from which exhaust gas and reductant arereceived and an outlet in fluid communication with an end of the exhaustsystem 190.

The exhaust system 190 may further include an oxidation catalyst (forexample a diesel oxidation catalyst (DOC)) in fluid communication withthe exhaust system 190 (e.g., upstream of the SCR catalyst 106 or theDPF 102) to oxidize hydrocarbons and carbon monoxide in the exhaust gas.

In some implementations, the DPF 102 may be positioned downstream of thedecomposition chamber or reactor 104. For instance, the DPF 102 and theSCR catalyst 106 may be combined into a single unit. In someimplementations, the dosing module 112 may instead be positioneddownstream of a turbocharger or upstream of a turbocharger.

The sensor 150 may be coupled to the exhaust system 190 to detect acondition of the exhaust gas flowing through the exhaust system 190. Insome implementations, the sensor 150 may have a portion disposed withinthe exhaust system 190; for example, a tip of the sensor 150 may extendinto a portion of the exhaust system 190. In other implementations, thesensor 150 may receive exhaust gas through another conduit, such as oneor more sample pipes extending from the exhaust system 190. While thesensor 150 is depicted as positioned downstream of the SCR catalyst 106,it should be understood that the sensor 150 may be positioned at anyother position of the exhaust system 190, including upstream of the DPF102, within the DPF 102, between the DPF 102 and the decompositionchamber 104, within the decomposition chamber 104, between thedecomposition chamber 104 and the SCR catalyst 106, within the SCRcatalyst 106, or downstream of the SCR catalyst 106. In addition, two ormore sensors 150 may be utilized for detecting a condition of theexhaust gas, such as two, three, four, five, or six sensors 150 witheach sensor 150 located at one of the foregoing positions of the exhaustsystem 190.

III. EXAMPLE MULTI-STAGE MIXER

FIG. 2 depicts a multi-stage mixer 200 according to an exampleembodiment. While a multi-stage mixer 200 is described in thisparticular embodiment, it is understood that the relevant structure inthis and similar embodiments may constitute other aftertreatmentcomponents such as a SCR catalyst, a perforated tube, a pipe, amanifold, a decomposition chamber or reactor, a doser, a dosing module,and others. The multi-stage mixer 200 is configured to receive exhaustgases (e.g., combustion gases from an internal combustion engine, etc.)and to provide the exhaust gases downstream with a substantially uniformflow distribution (e.g., flow profile, etc.). According to an exampleembodiment, the multi-stage mixer 200 is additionally configured toselectively dose the exhaust gases with a reductant (e.g., urea, dieselexhaust fluid (DEF), AdBlue®, etc.). Because the multi-stage mixer 200provides a substantially uniform flow distribution of the exhaust gasesand promotes mixing between exhaust gases and reductant, the multi-stagemixer 200 may also provide the exhaust gases downstream with asubstantially uniform reductant distribution (e.g., reductant profile,etc.).

The multi-stage mixer 200 includes an multi-stage mixer inlet 202 thatreceives the exhaust gases into the multi-stage mixer 200 and anmulti-stage mixer outlet 204 that provides the exhaust gases from themulti-stage mixer 200. According to various embodiments, the multi-stagemixer inlet 202 receives the exhaust gases from a diesel particulatefilter (e.g., the DPF 102, etc.) and the multi-stage mixer outlet 204provides the exhaust gases to the SCR catalyst 106.

Flows of fluid can be defined by a Reynolds number, which is related toa flow pattern of the fluid, and a Stokes number, which is related tothe behavior of particles suspended within the fluid. Depending on theReynolds number, the flow may be, for example, turbulent or laminar. Theflow of the exhaust gases into the multi-stage mixer inlet 202 can bedefined by a Reynolds number that is greater than 10⁴, indicating thatthe flow of the exhaust gases is turbulent. Because the flow of theexhaust gases into the multi-stage mixer inlet 202 is turbulent,self-similarity exists. Depending on the Stokes number, particles may bemore or less likely to follow the flow of fluid. The flow of reductantcan be defined by a Stokes number that is on the order of one indicatingthat the reductant is unlikely to follow the flow of exhaust gases whichposes a problem in conventional mixing devices. Advantageously, themulti-stage mixer 200 incorporates various components and devices hereinwhich cause the reductant to be mixed with the exhaust gases (e.g., byreducing the Stokes number of the reductant, etc.) such that thereductant is propelled through the multi-stage mixer 200 along with theexhaust gases. In this way, the multi-stage mixer 200 improves reductantmixing and reduces a risk associated with formation of deposits withinthe multi-stage mixer 200. In various embodiments, the multi-stage mixer200 is static and does not have components which move in response to thepassage of exhaust gases through the multi-stage mixer 200. In this way,the multi-stage mixer 200 may be less complex to manufacture and lessexpensive, and therefore more desirable, than aftertreatment componentswith moving components.

The multi-stage mixer 200 includes a plurality of flow devices thatsegment the multi-stage mixer 200 into a plurality of stages. Each ofthe plurality of flow devices is structured to alter the flow of theexhaust gases and reductant so that the plurality of flow devicescumulatively causes the exhaust gases to obtain a target flowdistribution and reductant the reductant to obtain a target uniformityindex (e.g., uniformity distribution, etc.) at the multi-stage mixeroutlet 204. Obtaining certain flow distributions and reductantuniformities indices is important in the operation of an aftertreatmentsystem. For example, it is desirable to obtain a uniform flowdistribution and reductant uniformity index at an inlet of an SCRcatalyst because such a flow distribution allows the SCR catalyst toobtain a relatively high conversion efficiency.

As shown in FIG. 2, the multi-stage mixer 200 includes a first flowdevice 206, a second flow device 208, a third flow device 210, and afourth flow device 212. It is understood that the multi-stage mixer 200may include any combination of the first flow device 206, the secondflow device 208, the third flow device 210, and the fourth flow device212, including combinations with multiple first flow devices 206,multiple second flow devices 208, multiple third flow devices 210,and/or multiple fourth flow devices 212 and combinations without a firstflow device 206, a second flow device 208, a third flow device 210,and/or a fourth flow device 212.

As the exhaust gases enter through the multi-stage mixer inlet 202,prior to the encountering the first flow device 206, the exhaust gasesare in stage zero. In stage zero, the exhaust gases have yet to beimpacted by any of the flow devices. The exhaust gases then flow throughthe first flow device 206. The first flow device 206 includes a numberof apertures N_(I) defining an open area A_(I) through which the exhaustgases flow into stage one. The apertures of the first flow device 206are defined by an average area A_(AI). The first flow device 206 may beconfigured to produce a Venturi, swirl, or mixing effect. The swirleffect may cause a majority of the flow of the exhaust gases to bebiased towards a periphery of the multi-stage mixer 200. The first flowdevice 206 may create a low pressure region in stage one. This lowpressure region may facilitate enhanced reductant decomposition (e.g.,via evaporation, via thermolysis, etc.), ordinary and turbulentdiffusion, and mixing of reductant droplets. The low pressure region mayalso draw exhaust flow and reductant from a periphery of the first flowdevice 206 into the first flow device 206.

The exhaust gases then flow through the second flow device 208. Thesecond flow device 208 includes a number of apertures N_(II) defining anopen area A_(II) through which the exhaust gases flow into stage two.The apertures of the second flow device 208 are defined by an averagearea A_(AII). The exhaust gases then flow through the third flow device210. The third flow device 210 includes a number of apertures N_(III)defining an open area A_(III) through which the exhaust gases flow intostage three. The apertures of the third flow device 210 are defined byan average area A_(AIII). The exhaust gases then flow through the fourthflow device 212. The fourth flow device 212 includes a number ofapertures N_(IV) defining an open area A_(IV) through which the exhaustgases flow into stage four. The apertures of the fourth flow device 212are defined by an average area A_(AIV). The fourth flow device 212 mayinclude a uniform or otherwise patterned perforated plate, where A_(AIV)is relatively small. In this way, the fourth flow device 212 can beconfigured to provide the exhaust gases to stage four with a uniformflow and distribution of reductant. From stage four, the exhaust gasesflow out of the multi-stage mixer outlet 204 of the multi-stage mixer200.

According to an example embodiment, the multi-stage mixer 200 isconfigured such that:

A _(I) ≈A _(II) ≈A _(III) ≈A _(IV)  (1)

A _(AI) ≠A _(AII) ≠A _(AIII) ≠A _(AIV)  (2)

N _(I) ≠N _(II) ≠N _(III) ≠N _(IV)  (3)

which allows a dynamic pressure of the exhaust gases to remainsubstantially the same within each of stage zero, stage one, stage two,stage three, and stage four. In various embodiments, the first flowdevice 206, the second flow device 208, the third flow device 210, andthe fourth flow device 212 are configured such that:

A _(AI) >A _(AII) >A _(AIII) >A _(AIV)  (4)

N _(I) <N _(II) <N _(III) <N _(IV)  (5)

which facilitates a gradual change in the flow of the exhaust gases byminimizing the pressure drops of the exhaust gases. The pressure drop ofthe exhaust gases are computed (e.g., determined) by subtracting thepressure of the exhaust gases at the multi-stage mixer outlet 204 fromthe pressure of the exhaust gases at the multi-stage mixer inlet 202. Invarious embodiments, the multi-stage mixer 200 is configured to decreasethe pressure drop when the associated internal combustion engine isoperating at a transient cycle (e.g., the Federal Test Procedure, WorldHarmonized Transient Cycle, Nonroad Transient Cycle, etc.), asteady-state cycle (e.g., the World Harmonized Stationary Cycle, etc.),or a combination thereof, compared to a conventional aftertreatmentsystem.

The multi-stage mixer 200 includes a doser 214 and a port 216 throughwhich reductant (e.g., reductant droplets, etc.) from the doser 214 isselectively introduced into the multi-stage mixer 200. According to anexample embodiment, the doser 214 is positioned within stage zero. Themulti-stage mixer 200 disperses the reductant uniformly within theexhaust gases that flow from the multi-stage mixer outlet 204 of themulti-stage mixer 200. The port 216 is configured to guide, or assist inguiding, the reductant towards a center (e.g., a center axis, center ofdomain, etc.) of the multi-stage mixer 200 regardless of the conditions(e.g., flow rate, temperature, etc.) of the exhaust gases. For example,the port 216 may have various shapes and/or thicknesses in order toguide the reductant towards the center of the multi-stage mixer 200.

In some embodiments, the multi-stage mixer 200 also includes a reductantguide 218 (e.g., nozzle, perforated tube, etc.) that at least partiallyshields the reductant from the flow of the exhaust gases from themulti-stage mixer inlet 202 to facilitate guiding of the reductant tothe center of the multi-stage mixer 200. The reductant guide 218 extendsfrom the port 216, receives the reductant from the doser 214, andprovides the reductant into the multi-stage mixer 200 (e.g., at a centerof the multi-stage mixer 200, etc.). In various embodiments, thereductant guide 218 is frustoconical.

In an example embodiment, the first flow device 206, the second flowdevice 208, the third flow device 210, and the fourth flow device 212are each symmetrical. Accordingly, manufacturing of the first flowdevice 206, the second flow device 208, the third flow device 210, andthe fourth flow device 212 is simplified and sizes of the first flowdevice 206, the second flow device 208, the third flow device 210, andthe fourth flow device 212 can be easily altered for variousapplications. In contrast, conventional aftertreatment devices typicallyincorporate an asymmetrical component that contacts flow. As a result,the multi-stage mixer 200 is more desirable than conventionalaftertreatment devices. Additionally, any of the first flow device 206,the second flow device 208, the third flow device 210, and the fourthflow device 212 may easily be replaced with another flow device suchthat the multi-stage mixer 200 is tailored for a target application.

Due to the specific configuration and construction of the multi-stagemixer 200, the multi-stage mixer 200 is scalable and easily configurablewhile maintaining the ability to provide exhaust gases having a highlyuniform flow and reductant profile while minimizing a pressure dropexperienced by the exhaust gases as well as minimizing the likelihood ofdeposit (e.g., urea deposit, etc.) formation. As a result, themulti-stage mixer 200 is capable of being configured for a targetapplication at a lower cost than other mixers which are not readilyadaptable (i.e., due to the scalability and modularity of themulti-stage mixer 200, etc.). The multi-stage mixer 200 and componentsthereof are scalable in the axial direction (e.g., in length, etc.) andthe radial direction (e.g., in diameter, etc.). For example, themulti-stage mixer 200 may be scaled to include additional or fewer flowdevices. In one example, the multi-stage mixer 200 may be scaled byincluding additional flow devices.

By being scalable, the multi-stage mixer 200 can be utilized in variousapplications where different lengths and/or diameters of the multi-stagemixer 200 are desired. For example, the multi-stage mixer may beproduced for use with an aftertreatment system of a maritime vessel inone size and produced for use with an aftertreatment system of a dieselcommercial vehicle in another size.

Because of the flexibility of the multi-stage mixer 200, the multi-stagemixer 200 is capable of being manufactured at a lower cost thanconventional aftertreatment devices and of being easily tailored to manyspecific applications, thereby making the multi-stage mixer 200 moredesirable than conventional aftertreatment devices. Further, themulti-stage mixer 200 may be configured for retrofit or drop-inapplications.

While the multi-stage mixer 200 is shown as including the first flowdevice 206, the second flow device 208, the third flow device 210, andthe fourth flow device 212, it is understood that the multi-stage mixer200 may include more or less flow devices such that the multi-stagemixer 200 is tailored for a target application. Further, the number,shape, and size of the apertures in any of the first flow device 206,the second flow device 208, the third flow device 210, and the fourthflow device 212 may be varied such that the multi-stage mixer 200 istailored for a target application. In some applications, the number offlow devices, and the configurations thereof, may be tailored to improvereductant decomposition, exhaust gas distribution, reductantdistribution within the exhaust gases, and minimization of pressure dropof the exhaust gases.

FIG. 3 illustrates the multi-stage mixer 200 according to oneembodiment. The multi-stage mixer 200 includes the first flow device206, the second flow device 208, and the third flow device 210. Thefirst flow device 206 is shown to include a funneling edge 300, aVenturi body 302, and a first support flange 304 (e.g., downstreamsupport flange, etc.). The funneling edge 300 is contiguous with theVenturi body 302 which is contiguous with the first support flange 304.The funneling edge 300 is configured to direct a majority of the exhaustgases from the multi-stage mixer inlet 202 into the Venturi body 302.However, the funneling edge 300 permits a portion of the exhaust gasesto initially circumvent the Venturi body 302 and enter a region betweenthe first flow device 206 and the multi-stage mixer 200. The funnelingedge 300 may have various angles relative to the center axis of themulti-stage mixer 200 (e.g., ninety degrees, forty-five degrees, thirtydegrees, fifteen degrees, etc.). Additionally, the funneling edge 300may have various heights, as will be explained in more detail herein,relative to an outer edge of the body (e.g., relative to an outerdiameter of the body, etc.). By adjusting the height of the funnelingedge 300, more or less of the exhaust gases can be directed into thefirst flow device 206 and more or less of the exhaust gases can bedirected around the first flow device 206 (e.g., in a circumvented flow,etc.).

The Venturi body 302 may be circular, conical, frustoconical,aerodynamic, or other similar shapes. The first support flange 304functions to couple the first flow device 206 to the multi-stage mixer200. In various embodiments, the first support flange 304 provides aseal between the Venturi body 302 and the multi-stage mixer 200 suchthat no exhaust gases may pass through or circumvent the first supportflange 304. As a result, the exhaust gases are redirected from the firstsupport flange 304 upstream for entry into the Venturi body 302.However, as explained in more detail herein, the first support flange304 in some embodiments has apertures through which the exhaust gasesmay pass to pass through the first flow device 206.

As shown in FIG. 3, the first flow device 206 includes an exhaust gasguide aperture 306 and an exhaust gas guide 307 which is coupled to theport 216. The exhaust gas guide 307 may be frustoconical. The exhaustgas guide 307 receives reductant from the doser 214 (not shown in FIG.3), through the port 216, and causes the reductant to flow into theVenturi body 302. The exhaust gas guide 307 is coupled to, or integratedwithin, the Venturi body 302 of the first flow device 206 around theexhaust gas guide aperture 306 such that the exhaust gases cannot flowbetween the exhaust gas guide 307 and the Venturi body 302. Instead, theexhaust gas guide 307 includes a plurality of apertures 308 that eachreceive the exhaust gases and direct the exhaust gases into the exhaustgas guide 307. The exhaust gases are then mixed with reductant from thedoser 214 within the Venturi body 302 and/or the exhaust gas guide 307.The flow of the exhaust gases into the exhaust gas guide 307 causes thereductant from the doser 214 to flow, along with the exhaust gases, intothe Venturi body 302 and towards the center of the multi-stage mixer200. In this way, the flow of reductant is assisted by the flow of theexhaust gases.

According to various embodiments, the reductant guide 218 is positionedwithin the exhaust gas guide 307. In these embodiments, the reductant isseparated from the exhaust gases until the reductant leaves thereductant guide 218 at which point the exhaust gases cause the reductantto travel towards the center of the multi-stage mixer 200. By initiallyseparating the reductant and the exhaust gases, build-up of reductantwithin the multi-stage mixer 200 may be minimized by minimizingimpingement on a spray wall of the multi-stage mixer 200.

According to various embodiments, the diameter of the Venturi body 302is:

0.25D ₀ ≤D _(C)≤0.9D ₀  (6)

where the Venturi body 302 is defined by a diameter D_(C) and theMulti-Stage Mixer 200 is defined by an inner diameter D₀ greater thanD_(C). The static pressure measured at the Venturi body 302 is given by

$\begin{matrix}{P_{C} = {P_{0} - {\left( {\left( \frac{D_{0}}{D_{C}} \right)^{4} - 1} \right)*\frac{1}{2}\rho \; \upsilon_{0}^{2}}}} & (7)\end{matrix}$

where P_(C) is the absolute static pressure at the Venturi body 302,where P₀ is the absolute static pressure upstream of the Venturi body302 (e.g., as measured by a pressure transducer, as measured by asensor, etc.), where ρ is the density of the exhaust gases, and where v₀is the flow velocity upstream of the Venturi body 302 (e.g., as measuredby a sensor, etc.). Due to the difference is diameter between theVenturi body 302 and the multi-stage mixer 200, the Venturi body 302creates a low pressure region. The low pressure region enhances (e.g.,increases, expedites, etc.) decomposition of reductant (e.g., viaevaporation, via thermolysis, etc.), ordinary and turbulent diffusion,and mixing of reductant droplets.

In some embodiments, the first flow device 206 also includes a mainmixer 309 having a plurality of main vanes 310 and a plurality of mainvane apertures 312 interspaced therebetween to provide a swirl flowthereby creating additional low pressure regions and facilitating mixingby elongating a mixing trajectory of the first flow device 206. The mainvanes 310 are attached to and conform to the Venturi body 302 such thatthe exhaust gases can only exit the Venturi body 302 through the mainvane apertures 312. The main vanes 310 are also attached to and conformto a main vane central hub 313 that is centered about the center axis ofthe Venturi body 302.

The main vanes 310 are static and do not move within the Venturi body302. In this way, the main mixer 309 may be less complex to manufactureand less expensive, and therefore more desirable, than aftertreatmentcomponents with complicated components that are expensive and requiredifficult and time intensive manufacturing. Rather than confining theflow of exhaust gases into a single path to create a swirl flow, themain vanes 310 provide several openings between adjacent main vanes 310,such that each of the main vanes 310 independently swirls the exhaustgases and such that the main vanes 310 collectively form the swirl flowin the exhaust gases.

The main vanes 310 are positioned (e.g., curved, angled, bent, etc.) tocause a swirl (e.g., mixing, etc.) flow of the exhaust gases and thereductant to form a mixture. In various embodiments, the main vanes 310are substantially straight (e.g., substantially disposed along a plane,having a substantially constant slope along the main vane 310, etc.). Inother embodiments, the main vanes 310 are curved (e.g., notsubstantially disposed along a plane, having different slopes along themain vane 310, having edges which are curved relative to the remainderof the main vane 310, etc.). In still other embodiments, adjacent mainvanes 310 are positioned so as to extend over one another. In theseembodiments, the main vanes 310 may be straight and/or curved. Inembodiments with multiple main vanes 310, each main vane 310 may beindependently configured so that the main vanes 310 are individuallytailored to achieve a target configuration of the first flow device 206such that the multi-stage mixer 200 is tailored for a targetapplication.

Each of the main vanes 310 is defined by a vane angle (e.g., relative toa center axis of the multi-stage mixer 200, etc.) that is related to theswirl produced by that main vane 310. The vane angle for each of themain vanes 310 may be different from the vane angle for any of theothers of the main vanes 310. According to various embodiments, thefirst flow device 206 includes main vanes 310 that have a vane angle ofbetween thirty degrees and eighty degrees. However, the main vanes 310may have other suitable vane angles. Similarly, the first flow device206 may include any number of the main vanes 310. In some embodiments,the first flow device 206 includes between four and twelve main vanes310.

The main vane apertures 312 collectively define the open area A_(I).However, the size of the main vane apertures 312 is related to, in part,the diameter of the main vane central hub 313. According to variousembodiments, the diameter of the main vane central hub 313 is given by

0.05D _(C) ≤D _(H)≤0.25D _(C)  (8)

where D_(H) is the diameter of the main vane central hub 313. Inapplication, any of the number of the main vanes 310, the vane angles ofthe main vanes 310, and the diameter of the main vane central hub 313may be varied to optimize improvements in the flow of the exhaust gasesand the reductant, the improvements in the mixing of the reductant, andthe improvements in minimizing pressure drop. The main mixer 309 may beconfigured such that the main vanes 310 are symmetrically orasymmetrically disposed about the main vane central hub 313.

The second flow device 208 shown in FIG. 3 includes a second flow devicecenter aperture 314 and a plurality of second flow device apertures 316.The second flow device center aperture 314 is aligned with the center ofthe first flow device 206 and/or with the center of the multi-stagemixer 200 and is surrounded by the plurality of second flow deviceapertures 316. In operation, the exhaust gases, along with thereductant, flow through the main vane apertures 312 and into stage one,and then flow through the second flow device center aperture 314 and thesecond flow device apertures 316, and into stage two. The second flowdevice center aperture 314 and the second flow device apertures 316collectively define the open area A_(II).

The swirl flow produced by the main vanes 310 may cause a majority ofthe flow of the exhaust gases and the reductant to be biased towards aperiphery of the multi-stage mixer 200. The second flow device centeraperture 314 and the second flow device apertures 316 may counter thisbias by creating a relatively lower flow restriction at the center, viathe second flow device center aperture 314, and a relatively greaterflow restriction near the periphery of the multi-stage mixer 200, viathe second flow device apertures 316. This interaction between the firstflow device 206 and the second flow device 208 improves flow anduniformity of the exhaust gases and the reductant while continuing tominimize pressure drop.

The third flow device 210 shown in FIG. 3 includes a plurality of thirdflow device apertures 318. The plurality of third flow device apertures318 may be substantially similar to the second flow device apertures316. In operation, the exhaust gases, along with the reductant, flowthrough the second flow device center aperture 314 and the second flowdevice apertures 316 and into stage two, and then flow through the thirdflow device apertures 318, and into stage three. The third flow deviceapertures 318 collectively define the open area A_(III). From stagethree, the exhaust gases, along with the reductant, flow out of themulti-stage mixer 200 through the multi-stage mixer outlet 204.

The third flow device apertures 318 may be identical to one another anduniformly spaced along the third flow device 210. In this way, the thirdflow device 210 can provide a substantially uniform flow anddistribution of the exhaust gases and the reductant. In this way, thethird flow device 210 may reduce or eliminate shear experienceddownstream of the multi-stage mixer 200, such as at the inlet of the SCRcatalyst 106, which minimizes erosion, such as that typicallyexperienced by catalyst material due to contact with hard aerosolparticles entrained in swirling flow of exhaust gases.

FIG. 4 illustrates the multi-stage mixer 200 according to anotherembodiment. As shown in FIG. 4, the funneling edge 300 of the first flowdevice 206 is less angled than the funneling edge 300 shown in FIG. 3.As a result, a larger amount of the exhaust gases may flow between theVenturi body 302 and the multi-stage mixer 200 in the multi-stage mixer200 shown in FIG. 4 than in the multi-stage mixer 200 shown in FIG. 3.Further, the multi-stage mixer 200 shown in FIG. 4 does not include theexhaust gas guide 307 as shown in the multi-stage mixer 200 shown inFIG. 3 or the reductant guide 218. Rather, the reductant is output fromthe doser 214 (not shown in FIG. 4) through the port 216 and into theVenturi body 302 through the exhaust gas guide aperture 306. Thereductant guide 218 may be coupled to the Venturi body 302 around theexhaust gas guide aperture 306 so that no exhaust gas flows between thecylindrical body and the reductant guide 218. In this way, the reductantmixes with the exhaust gases within the Venturi body 302. Alternatively,a gap may exist between the reductant guide 218 and the Venturi body 302such that the reductant flows into the region between the Venturi body302 and the multi-stage mixer 200 and mixes with the exhaust gasesthere. From there, the exhaust gases and reductant may flow through theexhaust gas guide aperture 306 into the Venturi body 302.

As shown in FIG. 4, the first flow device 206 further includes aplurality of internal plates 400 disposed along the Venturi body 302.After reductant enters the Venturi body 302 via the exhaust gas guideaperture 306, the reductant falls into the Venturi body 302 and maycontact any of the internal plates 400. Contact between the internalplates 400 and the reductant helps to guide the reductant along a targettrajectory prior to reaching the main mixer 309, the second flow device208, the third flow device 210, or any other downstream component orfeature of the multi-stage mixer 200. In this way, the internal plates400 provide a suitable degree of pre-mixing, thereby improving auniformity index (e.g., a spatial distribution of the reductant relativeto the NO_(x) in the exhaust gases, etc.) of the exhaust gases.Additionally, the internal plates 400 may help reduce a droplet size ofthe reductant, thereby reducing the Stokes number of the reductant whichincreases the ability of the reductant to mix with the exhaust gases. Inthis way, the internal plates facilitate improved scalability of themulti-stage mixer 200. The number, shape, size, angle (e.g., vane angle,etc.), and configuration of the internal plates 400 may be varied suchthat the multi-stage mixer 200 obtains a relatively uniform flow of theexhaust gases and the reductant and a relatively uniform distribution ofthe reductant within the exhaust gases while minimizing sprayimpingement on the walls of the multi-stage mixer.

While the plurality of internal plates 400 have only been shown in FIG.4 herein, it is understood that all embodiments of the multi-stage mixer200 may include the plurality of internal plates 400 in any of the firstflow device 206, the second flow device 208, the third flow device 210,and the fourth flow device 212 described herein.

FIG. 5 illustrates the multi-stage mixer 200 according to anotherembodiment. As shown in FIG. 5, the exhaust gases flow into the Venturibody 302 of the first flow device 206 and the reductant is introducedinto the Venturi body 302 via the exhaust gas guide aperture 306 and thereductant guide 218 (not shown) which extends into the exhaust gas guide307. In some embodiments, the exhaust gas guide 307 is coupled to, orintegrated within, the multi-stage mixer 200. In other embodiments, theexhaust gas guide 307 is spaced from the multi-stage mixer 200 such thatthe exhaust gases can flow between the exhaust gas guide 307 and thewall of the multi-stage mixer 200. The first flow device 206 shown inFIG. 5 does not include the main mixer 309 shown in FIGS. 3 and 4.Instead, the exhaust gases and the reductant flow directly from insidethe Venturi body 302 into stage one and then through the second flowdevice apertures 316 in the second flow device 208. In this way, theVenturi body 302 defines the open area A_(I).

While the second flow device 208 does not include the second flow devicecenter aperture 314 shown in FIG. 3, the second flow device apertures316 shown in FIG. 5 are larger than the second flow device apertures 316shown in FIG. 1. Therefore, the second flow device apertures 316 shownin FIG. 5 define the open area A_(II) which is substantially equal tothe open area A_(I) of the first flow device 206. As shown in FIG. 5,the third flow device 210 includes a third flow device center aperture500. The exhaust gases and the reductant flow from the second flowdevice apertures 316 in the second flow device 208, into stage two, andthrough the third flow device 210 through the third flow device centeraperture 500, and into stage three. The third flow device centeraperture 500 defines the open area A_(III). From stage three, theexhaust and the reductant flow through a plurality of fourth flow deviceapertures 502 in the fourth flow device 212. The fourth flow deviceapertures 502 may be a plurality of perforations. The fourth flow deviceapertures 502 define the open area A_(VI). From stage four, the exhaustgases and the reductant flow out of the multi-stage mixer 200 via themulti-stage mixer outlet 204.

FIGS. 6A-6C illustrate the multi-stage mixer 200 and components thereofaccording to another embodiment. As shown in FIG. 6A, the first flowdevice 206 and the third flow device 210 are each replaced with a fifthflow device 600. The fifth flow device 600 includes a fifth flow devicecenter aperture 602. Further, the fifth flow device 600 does not includethe funneling edge 300, the Venturi body 302, or the exhaust gas guideaperture 306. The exhaust gases flow into the multi-stage mixer 200 andthe reductant is introduced to the exhaust gases via the exhaust gasguide 307. The exhaust gases and the reductant together flow through thefifth flow device center aperture 602 in the fifth flow device 600 andinto stage one. As shown in FIG. 6B, the fifth flow device centeraperture 602 may be centrally disposed within the fifth flow device 600.In this way, the fifth flow device center aperture 602 defines the openarea A_(I). From stage one, the exhaust gases and the reductant flowfrom stage one through the second flow device apertures 316 in thesecond flow device 208 and into stage two. As shown in FIG. 6C, thesecond flow device apertures 316 may be identical and uniformlycircumferentially disposed about the center axis of the second flowdevice 208. From stage two, the exhaust gases and the reductant flowfrom stage two through the fifth flow device center aperture 602 in thefifth flow device 600 and into stage three. In this way, the fifth flowdevice center aperture 602 defines the open area A₁₁₁ which is equal tothe open area A_(I). From stage three, the exhaust gases and thereductant flow from stage three through the fourth flow device apertures502 and into stage four.

FIG. 7 illustrates velocity of flows lines of the exhaust gases, andpotentially the reductant, within the multi-stage mixer 200 thatincludes the first flow device 206, the second flow device 208, and thethird flow device 210. FIG. 7 was generated using a simulation which hada change in absolute pressure of five-hundred and twenty-one Pascals ata mass flow rate of 8.5 kilograms per minute and at three-hundred andthirty-five degrees Celsius. As shown in FIG. 7, the flow lines enterthe multi-stage mixer 200 relatively straight, are imparted a swirl flowby the first flow device 206, and are subsequently straightened by thesecond flow device 208 and the third flow device 210 until the flowlines are relatively straight before exiting the multi-stage mixer 200.

FIG. 8 illustrates locations of reductant droplets and theircorresponding sizes within the multi-stage mixer 200 that includes thefirst flow device 206, the second flow device 208, the third flow device210, and the port 216. As shown in FIG. 8, the reductant droplets enterthe multi-stage mixer 200, are imparted a swirl flow by the first flowdevice 206, and are subsequently uniformly dispersed by the second flowdevice 208 and the third flow device 210 until the reductant dropletsare relatively uniformly dispersed before exiting the multi-stage mixer200.

FIGS. 9A-9G illustrate a sixth flow device 900 according to variousembodiments. The sixth flow device 900 may be any of the first flowdevice 206, the second flow device 208, the third flow device 210, thefourth flow device 212, and the fifth flow device 600 as describedherein.

The sixth flow device 900 includes a plurality of sixth flow deviceapertures 902. By increasing the size the sixth flow device apertures902 within the sixth flow device 900, flow of the exhaust gases and thereductant may become more uniform and distribution of the reductantwithin the exhaust gases may also become more uniform. These samebenefits may be achieved by increasing the density of the sixth flowdevice apertures 902 proximate to the center of the sixth flow device900.

In other applications, the sixth flow device apertures 902 may beuniformly distributed about a central region 904, as shown in FIG. 9D.The central region 904 may include additional sixth flow deviceapertures 902 which are uniformly distributed within the central region904. As shown in FIG. 9D, the sixth flow device 900 is configured suchthat the sixth flow device apertures 902 that are not disposed withinthe central region 904 are less heavily concentrated than the sixth flowdevice apertures 902 that are disposed within the central region 904.

As shown in FIG. 9A, the sixth flow device apertures 902 are uniformlydistributed across the sixth flow device 900 and the sixth flow deviceapertures 902 are identical. In this way, flow produced by the sixthflow device 900 may be substantially uniform. Such an arrangement of thesixth flow device 900 may be implemented proximate to the multi-stagemixer outlet 204 of the multi-stage mixer 200.

However, the sixth flow device apertures 902 may also have differentsizes and the sixth flow device apertures 902 may be arranged accordingto their sizes. As shown in FIGS. 9B and 9C, the sixth flow deviceapertures 902 are uniformly distributed across the sixth flow device 900with larger sixth flow device apertures 902 being arranged near thecenter of the sixth flow device 900 and smaller sixth flow deviceapertures 902 being arranged near the perimeter of the sixth flow device900. Such an arrangement of the sixth flow device 900 may be implementedafter a swirl has been formed (e.g., after the first flow device 206,etc.).

In other applications, the sixth flow device apertures 902 may beuniformly distributed about a central region 904. The central region 904may include additional sixth flow device apertures 902 which areuniformly distributed within the central region 904. As shown in FIG.9D, the sixth flow device 900 is configured such that the sixth flowdevice apertures 902 that are not disposed within the central region 904are less heavily concentrated than the sixth flow device apertures 902that are disposed within the central region 904. In still otherapplications, the sixth flow device apertures 902 may be uniformlydistributed about a central aperture 906. As shown in FIG. 9E, the sixthflow device 900 is configured such that the sixth flow device apertures902 are uniformly disposed around the central aperture 906.

In some applications, each of the sixth flow device apertures 902includes a sixth flow device vane 908 that is contiguous with the sixthflow device aperture 902. As shown in FIG. 9F, the sixth flow deviceapertures 902 are semi-circular and the sixth flow device vanes 908 aresemi-circular. As shown in FIG. 9G, the sixth flow device apertures 902are square and the sixth flow device vanes 908 are square. Inmanufacture, the sixth flow device apertures 902 and the sixth flowdevice vanes 908 may be formed simultaneously (e.g., via a punch anddie, etc.).

The sixth flow device vanes 908 may be configured to cause the exhaustgases and the reductant to flow in a target direction. The sixth flowdevice apertures 902 and the sixth flow device vanes 908 may be arrangedin a plurality of row and columns across the sixth flow device 900. Asshown in FIGS. 9F and 9G, the direction of the sixth flow device vanes908 may be alternated within a row and be the same within a column.However, other arrangements and configurations of the sixth flow devicevanes 908 and the sixth flow device apertures 902 are also possible. Forexample, the sixth flow device vanes 908 and the sixth flow deviceapertures 902 may cooperate to create a swirl flow.

FIGS. 10A-10D illustrate the exhaust gas guide 307 in more detailaccording to various embodiments. It is understood that the exhaust gasguide 307 as shown and described with reference to FIGS. 10A-10D may beincluded in any of the embodiments of the multi-stage mixer 200discussed herein.

As shown in FIGS. 10A and 10B, the reductant guide 218 is positionedwithin the exhaust gas guide 307. The reductant guide 218 is configuredto dose reductant past the exhaust gas guide 307 and into themulti-stage mixer 200. The exhaust gas guide 307 is defined by a firstangle (e.g., at an apex, etc.) and the multi-stage mixer 200 is definedby a second angle (e.g., at an apex, etc.) that is less than the firstangle. In this way, the exhaust gas guide 307 and the multi-stage mixer200 are configured such that spray impingement on the exhaust gas guide307 is minimized.

The apertures 308 are positioned along the exhaust gas guide 307 and areconfigured to direct the exhaust gases into a region between the exhaustgas guide 307 and the reductant guide 218 such that the exhaust gasesare directed out of a nozzle 1000 of the exhaust gas guide 307.Reductant from the reductant guide 218 may become entrained within theexhaust gases and thereby ejected from the exhaust gas guide 307 alongwith the exhaust gases. As shown in FIG. 10A, the apertures 308 aredisposed along a leading surface 1002 of the exhaust gas guide 307. Theleading surface 1002 is adjacent the flow of the exhaust gases from themulti-stage mixer inlet 202 (e.g., upstream, etc.) of the multi-stagemixer 200. The leading surface 1002 may be defined by an angular segmentof the exhaust gas guide 307. For example, the leading surface 1002 maybe approximately one-hundred and twenty degrees of the exhaust gas guide307 that is centered on a direction of flow of the exhaust gases intothe exhaust gas guide 307.

The apertures 308 may be of varying shapes, sizes, pitches, densities,and configurations. The apertures 308 may be, for example, configured toguide the exhaust gases out of the nozzle 1000 in a vertical direction(e.g., relative to the flow of the exhaust gases into the multi-stagemixer inlet 202. For example, as shown in FIG. 10B, the apertures 308are disposed uniformly along the exhaust gas guide 307. In anotherexample shown in FIG. 10C, the apertures 308 are disposed along theleading surface 1002. However, as shown in FIG. 10C, the exhaust gasguide 307 includes a cylindrical section 1006 that does not include anyapertures 308. The cylindrical section 1006 may facilitate use of theexhaust gas guide 307 in applications where space is limited. Further,in FIG. 10D, the exhaust gas guide 307 includes a deformed section 1008that also facilitates use of the exhaust gas guide 307 in applicationswhere space is limited.

FIGS. 11A-11E illustrate a portion of the first flow device 206according to various embodiments. In some embodiments, the main mixer309 includes a complementary vane 1100 positioned on each of the mainvanes 310. It is understood that the complementary vanes 1100 as shownand described with reference to FIGS. 11A-11E may be included in any ofthe embodiments of the multi-stage mixer 200 discussed herein.

The complementary vanes 1100 define complementary apertures 1102 whichare contiguous with the main vane apertures 312. In this way, thecomplementary vanes 1100 increase the open area, A_(I), of the firstflow device 206. The complementary vanes 1100 may be configured withvarious angles relative to the main vanes 310 and with various shapes,sizes and configurations. For example, the first flow device 206 may beconfigured with some of the main vanes 310 including the complementaryvanes 1100 and others of the main vanes 310 not including thecomplementary vanes 1100.

The complementary vanes 1100 may be positioned to be contiguous with anedge of each of the main vanes 310, as shown in FIGS. 11A and 11D, or tobe positioned within the main vanes 310, as shown in FIGS. 11B and 11C.Additionally, the complementary vanes 1100 may be configured to create aswirl flow (e.g., co-swirl flow, counter-swirl flow, etc.) that isseparate from the swirl flow created by the main vanes 310. In this way,the complementary vanes 1100 can be utilized to increase or decrease thetotal swirl created by the first flow device 206. In some embodiments,multi-stage mixing can be achieved in an axial direction through the useof two flow devices (e.g., the first flow device 206, the second flowdevice 208, etc.) that include the complementary vanes 1100.

FIG. 11E illustrates a cross-sectional view of the multi-stage mixer 200having the first flow device 206 including the complementary vanes 1100.In this embodiment, the auxiliary mixer 1106 is eliminated. Theauxiliary mixer 1106 may not be needed, and could be eliminated toreduce the cost and manufacturing complexity of the multi-stage mixer200, in some applications of the multi-stage mixer 200. For example, theauxiliary mixer 1106 may not be included in the multi-stage mixer 200when the multi-stage mixer 200 is placed downstream of a turbocharger ina close-coupled arrangement (e.g., where the multi-stage mixer 200 isdisposed in close proximity to an outlet of the turbocharger, etc.)because the turbocharger produces relatively high swirl velocities atthe multi-stage mixer inlet 202.

As shown in FIG. 12A, the first flow device 206 includes an auxiliarymixer 1106 that includes auxiliary vanes 1108. It is understood that theauxiliary mixer 1106 as shown and described with reference to FIG. 12Amay be included in any of the embodiments of the multi-stage mixer 200discussed herein.

The auxiliary vanes 1108 are attached to an auxiliary vane central hub1109 that is centered about the center axis of the multi-stage mixer200. The auxiliary vane central hub 1109 is coupled to the Venturi body302 (e.g., via members interspacing adjacent auxiliary vanes 1108,etc.). The auxiliary mixer 1106 is configured to receive the exhaustgases from the multi-stage mixer inlet 202 and to provide the exhaustgases into the Venturi body 302. The auxiliary vanes 1108 may be similarto or different from the main vanes 310. Tips (e.g., outermost surfaces,etc.) of each of the auxiliary vanes 1108 may be spaced from the Venturibody 302 by an air gap such that the exhaust gases can pass between thetips of each of the auxiliary vanes 1108 and the Venturi body 302.

The auxiliary mixer 1106 includes a plurality of auxiliary vaneapertures 1110 interspaced between the plurality of auxiliary vanes1108. In this way, the plurality of auxiliary vanes and the plurality ofauxiliary vane apertures 1110 provide a swirl flow within the first flowdevice 206. The plurality of auxiliary vane apertures 1110 cooperatewith the plurality of auxiliary vanes 1108 to provide the exhaust gasesinto the first flow device 206 with a swirl flow that facilitates mixingof the reductant and the exhaust gases. The auxiliary vanes 1108 may beconfigured to create a swirl flow (e.g., co-swirl flow, counter-swirlflow, etc.) that is separate from the swirl flow created by the mainvanes 310 and/or the complementary vanes 1100. In this way, theauxiliary vanes 1108 can be utilized to increase or decrease the totalswirl created by the first flow device 206. Further, the auxiliary vanes1108 may increase mixing of the reductant and the exhaust gases withinthe Venturi body 302.

In the embodiment shown in FIG. 12A, the auxiliary vanes 1108 arelocated upstream of where the reductant is introduced while thecomplementary vanes 1100 and the main vanes 310 are located downstreamof where the reductant is introduced. In this embodiment, the auxiliaryvanes 1108 create a first swirl flow in a first direction and the mainvanes 310 and/or the complementary vanes 1100 create a second swirl flowin a second direction that may be the same as the first direction (e.g.,co-swirl flow, etc.) or opposite to the first direction (e.g.,counter-swirl flow, etc.). Rather than confining the flow of exhaustgases into a single path to create a swirl flow, the auxiliary vanes1108 provide several openings between adjacent auxiliary vanes 1108,such that each of the auxiliary vanes 1108 independently swirls theexhaust gases and such that the auxiliary vanes 1108 collectively formthe swirl flow in the exhaust gases.

The main vanes 310 and/or the auxiliary vanes 1108 may be constructed(e.g., manufactured, made, etc.) using sheet metal (e.g., aluminumsheets, steel sheets, etc.) in various applications. For example, themain vanes 310 and/or the auxiliary vanes 1108 may be constructedthrough stamping, punching, laser cutting, waterjet cutting, and/orwelding operations.

FIG. 12B illustrates a cross-sectional view of the multi-stage mixer 200having the auxiliary mixer 1106 including the complementary vanes 1100and the second flow device 208 including a plurality of second flowdevice vanes 1200. It is understood that the second flow device vanes1200 as shown and described with reference to FIG. 12B may be includedin any of the embodiments of the multi-stage mixer 200 discussed herein.

The second flow device vanes 1200 may be similar to or different fromthe main vanes 310. Similar to the complementary vanes 1100 and theauxiliary vanes 1108, the second flow device vanes 1200 may beconfigured to create a swirl flow (e.g., co-swirl flow, counter-swirlflow, etc.) that is separate from the swirl flow created by the mainvanes 310, the complementary vanes 1100, and/or the auxiliary vanes1108. In this way, the second flow device vanes 1200 can be utilized toincrease or decrease the total swirl of the exhaust gases and thereductant. In the embodiment shown in FIG. 12B, the complementary vanes1100 and the second flow device vanes 1200 are located downstream ofwhere the reductant is introduced. In this embodiment, the complementaryvanes 1100 create a first swirl flow in a first direction and the secondflow device vanes 1200 create a second swirl flow in a second directionthat may be the same as the first direction (e.g., co-swirl flow, etc.)or opposite to the first direction (e.g., counter-swirl flow, etc.).

FIG. 13 illustrates a cross-sectional view of the multi-stage mixer 200having the first flow device 206 and the auxiliary mixer 1106. While notshown in FIG. 13, it is understood that the multi-stage mixer 200 mayinclude the exhaust gas guide 307. The auxiliary mixer 1106 is locatedupstream of the exhaust gas guide aperture 306 and the first flow device206 is located downstream of the exhaust gas guide aperture 306. Theauxiliary mixer 1106 functions to create a swirl flow of the exhaustgases within the first flow device 206 downstream the auxiliary mixer1106. The swirl flow created by the auxiliary mixer 1106 facilitatesdistribution of the reductant in the exhaust gases between the auxiliarymixer 1106 and the main vanes 310 such that the reductant issubstantially evenly distributed within the exhaust gases when theexhaust gases encounter the main vanes 310. Additionally, the swirl flowcreated by the auxiliary mixer 1106 creates a relatively large shear atthe Venturi body 302 (e.g., the portion of the Venturi body 302 betweenthe auxiliary vanes 1108 and the main vanes 310, etc.) to reduce theformation of a film, and therefore the accumulation of deposits, alongthe Venturi body 302. The main vanes 310 function to impart a swirl flowon the exhaust gases and entrained reductant downstream of the firstflow device 206. This swirl flow causes the exhaust gases to berelatively uniform (e.g., in terms of reductant composition, etc.)downstream of the first flow device 206, such as at the multi-stagemixer outlet 204 (e.g., proximate an inlet of the SCR catalyst 106,etc.).

The Venturi body 302 is defined by a body center axis 1300. The Venturibody 302 is centered on (e.g., a centroid of the Venturi body 302 iscoincident with, etc.) the body center axis 1300. The auxiliary vanes1108 and the main vanes 310 are also centered on the body center axis1300. The first support flange 304 is defined by a mixer center axis1302. In addition to the benefits of the auxiliary vanes 1108 and themain vanes 310 in mixing the reductant in the exhaust gases, the firstsupport flange 304 is configured, such that the body center axis 1300 isoffset from the mixer center axis 1302 by a radial offset h_(r). Theradial offset h_(r) causes any reductant build up on the Venturi body302 (e.g., non-uniform distribution of the reductant in the exhaustgases within the first flow device 206, etc.) to be substantiallyredistributed to the exhaust gases downstream of the first flow device206. While the body center axis 1300 is offset from the mixer centeraxis 1302 towards the port 216 by the radial offset h_(r) in FIG. 13, itis understood that the body center axis 1300 may be offset from themixer center axis 1302 away from the port 216 by the radial offseth_(r), or offset from the mixer center axis 1302 towards the Venturibody 302 (e.g., orthogonally to the port 216, etc.) by the radial offseth_(r).

The Venturi body 302 has a body inlet 1304 and a body outlet 1306. Theinlet has a diameter d_(v) and the outlet has a diameter d_(s) which isless than the diameter d_(v). The diameter d_(v) and the diameter d_(s)are each less than the diameter D₀ of the multi-stage mixer 200. Invarious embodiments, the multi-stage mixer 200 and the first flow device206 are configured such that

0.4D ₀ ≤d _(v)≤0.9D ₀  (9)

0.7d≤d _(s) ≤d _(v)  (10)

0≤h _(r)≤0.1D ₀  (11)

In various embodiments, the first support flange 304 does not protrudeinto the Venturi body 302 (e.g., the first support flange 304 defines anaperture contiguous with the Venturi body 302 and having a diameterequal to the diameter d_(s), etc.).

In various embodiments, the funneling edge 300 radially protrudes fromthe body inlet 1304 towards the multi-stage mixer 200 a distance h_(i).In various embodiments, the first flow device 206 is configured suchthat

0≤h _(i)≤0.1d _(v)  (12)

By varying the distance h_(i), the flows of the exhaust gas into thefirst flow device 206 and/or the exhaust gas guide aperture 306 may beoptimized.

The reductant flows from the port 216 through the exhaust gas guideaperture 306. The exhaust gas guide aperture 306 is generally circularand defined by a diameter d_(e). In various embodiments, the first flowdevice 206 is configured such that

$\begin{matrix}{d_{e} = {\left( {D_{0} - d_{v} - {2h_{r}}} \right)*{\tan \left( \frac{\alpha + \delta}{2} \right)}}} & (13)\end{matrix}$

where

5°≤δ≤20°  (14)

where δ is a margin that is selected based on the configuration of thefirst flow device 206 and where a is a spray angle of the nozzle 1000.In some embodiments the exhaust gas guide aperture 306 is elliptical. Inthese embodiments, the diameter d_(e) may be a major axis (e.g., asopposed to a minor axis, etc.) of the exhaust gas guide aperture 306.

The first flow device 206 is also defined by a spacing L_(m) between atrailing edge of the auxiliary vanes 1108 and a trailing edge of themain vanes 310. In various embodiments, the first flow device 206 isconfigured such that

$\begin{matrix}{d_{e} \leq L_{m} \leq \frac{d_{e}\left( {D + d_{v} - {2h_{r}}} \right)}{\left( {D - d_{v} - {2h_{r}}} \right)}} & (15)\end{matrix}$

The Venturi body 302 includes a shroud 1308. It is understood that theshroud 1308 as shown and described with reference to FIG. 13 may beincluded in any of the embodiments of the multi-stage mixer 200discussed herein.

The shroud 1308 defines a downstream end of the Venturi body 302 and istherefore defined by the diameter d_(s). In various embodiments, theshroud 1308 is cylindrical or conical (e.g., frustoconical, etc.) inshape. The shroud 1308 may facilitate a reduction in stratification ofthe exhaust gases that occurs from centrifugal force created by the mainmixer 309. Additionally, the shroud 1308 may provide structural supportto the main mixer 309, such as when the main vanes 310, in addition tothe main vane central hub 313, are attached to the shroud 1308 (e.g.,such that the main vanes 310 conform to the shroud 1308, etc.). When themain vanes 310 are attached to the shroud 1308, the main vanes 310 mayprovide a more directed swirl flow (e.g., along a target trajectory,etc.) by removing leak paths, thereby improving mixing performance(e.g., the ability of the main mixer 309 to mix the reductant andexhaust gases, etc.) and reducing the accumulation of depositsdownstream of the main mixer 309 (e.g., in the shroud 1308, in theexhaust component downstream of the multi-stage mixer 200, etc.).Furthermore, the shroud 1308 substantially prevents leakage flow andliquid film accumulation and mitigates the formation of deposits withinthe first flow device 206 (e.g., on the Venturi body 302, etc.) and/orthe multi-stage mixer 200. The shroud 1308 is defined by an angle(relative to an axis parallel to the body center axis 1300 and the mixercenter axis 1302. In various embodiments, the first flow device 206 isconfigured such that

Φ≤50°  (16)

In various embodiments, the first flow device 206 is configured suchthat

$\begin{matrix}{L_{s} = \frac{d_{v} - d_{s}}{2*\tan \; \Phi}} & (17)\end{matrix}$

where L_(s) is the length of the shroud 1308. Where the shroud 1308 iscylindrical, the diameter d_(s) is equal to the diameter d_(v) and

0.02d _(v) ≤L _(s)≤0.25d _(v)  (18)

In some embodiments, at least one of the flow devices of the multi-stagemixer 200 is angled relative to the mixer center axis 1302. For example,the first flow device 206 may be configured such that the body centeraxis 1300 is tilted up from (e.g., angled at a positive angle relativeto, etc.) the mixer center axis 1302 or such that the body center axis1300 is tilted down from (e.g., angled at a negative angle relative to,etc.) the mixer center axis 1302.

FIG. 14 illustrates a variation of the first flow device 206 shown inFIG. 13. In FIG. 14, the auxiliary vanes 1108 are shown spaced from theVenturi body 302 by a gap g. In various embodiments, the first flowdevice 206 is configured such that

0≤g≤0.15d _(v)  (19)

The gap g may mitigate accumulation of reductant deposits on the Venturibody 302. The gap g functions to create a substantially axial flow ofexhaust gases directed along the Venturi body 302 (e.g., on the innersurfaces of the Venturi body 302, etc.). In this way, the gap g maybalance flow (e.g., a main tangential flow, etc.) of the exhaust gasesthrough the auxiliary vanes 1108 with the aforementioned axial flow anda flow of the exhaust gases around the first flow device 206. Insteadof, or in addition to, the gap g, the auxiliary vanes 1108 may includeslots (e.g., thin slots) or holes through which the exhaust gases mayflow. For example, each of the auxiliary vanes 1108 may include a slotcontiguous with an outermost edge of the auxiliary vane 1108. In thisexample, the exhaust gases may flow through the slot and against theVenturi body 302 proximate the slot, thereby providing benefits similarto those of the gap g.

Also shown in FIG. 14, the main vanes 310 are shown in contact with theshroud 1308 such that no gap exists between at least a portion of eachof the main vanes 310 and the shroud 1308. In an example embodiment, thetip (e.g., the most radially outward surface, etc.) of each of the mainvanes 310 is welded (e.g., fused, etc.) to the shroud 1308.

In some embodiments, the main vanes 310 may be spaced from the shroud1308 by a gap g_(v). In various embodiments, the first flow device 206is configured such that

0≤g _(v)≤0.15d _(v)  (20)

The gap g_(v) may mitigate accumulation of reductant droplets on theshroud 1308. The gap g_(v) functions to create a substantially axialflow of exhaust gases directed along the shroud 1308 (e.g., on innersurfaces of the shroud 1308, etc.). Instead of, or in addition to, thegap g_(v), the main vanes 310 may include slots (e.g., thin slots) orholes through which the exhaust gases may flow. For example, each of themain vanes 310 may include a slot contiguous with an outermost edge ofthe main vane 310. In this example, the exhaust gases may flow throughthe slot and against the shroud 1308 proximate the slot, therebyproviding benefits similar to those of the gap g.

In an some embodiments, the tip of each of the auxiliary vanes 1108 isattached (e.g., welded, coupled, etc.) to the Venturi body 302 (e.g.,such that the auxiliary vanes 1108 conform to the Venturi body 302,etc.). When the auxiliary vanes 1108 are attached to the Venturi body302, the auxiliary vanes 1108 may provide a more directed swirl flow(e.g., along a target trajectory, etc.) by removing leak paths, therebyimproving mixing performance (e.g., the ability of the auxiliary mixer1106 to mix the reductant and exhaust gases, etc.) and reducing theaccumulation of deposits downstream of the auxiliary mixer 1106 (e.g.,in the Venturi body 302, on the main mixer 309, in the exhaust componentdownstream of the multi-stage mixer 200, etc.). In FIG. 13, theauxiliary vanes 1108 are shown in contact with the Venturi body 302 suchthat no gap exists between at least a portion of each of the auxiliaryvanes 1108 and the Venturi body 302.

Each of the auxiliary vanes 1108 is defined by an auxiliary vane anglerelative to an auxiliary vane central hub center axis of the auxiliaryvane central hub 1109 of the auxiliary vanes 1108. Similarly, the mainvane angle for each of the main vanes 310 is defined relative to a mainvane central hub center axis of the main vane central hub 313. Theauxiliary vane angle for each of the auxiliary vanes 1108 may bedifferent from the auxiliary vane angle for any of the others of theauxiliary vanes 1108. In various embodiments, the auxiliary vane anglefor each of the auxiliary vanes 1108 is between forty five degrees andninety degrees, inclusive, relative to a main vane central hub centeraxis of the main vane central hub 313 and the main vane angle for eachof the main vanes 310 is between forty five degrees and ninety degrees,inclusive. The auxiliary vane angle for each of the auxiliary vanes 1108may be selected such that the first flow device 206 is tailored for atarget application. Similarly, the main vane angle for each of the mainvanes 310 may be selected such that the first flow device 206 istailored for a target application. The auxiliary mixer 1106 may beconfigured such that the auxiliary vanes 1108 are symmetrically orasymmetrically disposed about the auxiliary vane central hub 1109.

The auxiliary vane angle may be different for each of the auxiliaryvanes 1108 and the main vane angle may be different from each of themain vanes 310. Selection of the auxiliary vane angle for each of theauxiliary vanes 1108 and the main vane angle for each of the main vanes310 may be made so as to create asymmetric swirl of the exhaust gases,to direct flow of the exhaust gases (e.g., towards a target location inthe multi-stage mixer 200, etc.), to more uniformly distribute reductantwithin the exhaust gases, and to reduce deposits within the first flowdevice 206 (e.g., on the Venturi body 302, etc.) and/or the multi-stagemixer 200.

FIG. 15 illustrates the first flow device 206 with a main mixer 309having six of the main vanes 310, where four of the main vanes 310 eachhave a first vane angle and two of the main vanes 310 have a second vaneangle that is larger than the first vane angle. FIG. 16 illustrates themain vanes 310 of the first flow device 206 shown in FIG. 15.

FIG. 17 illustrates the first flow device 206 with a main mixer 309having six of the main vanes 310, where four of the main vanes 310 eachhave a first vane angle that is not equal to forty five degrees suchthat the four main vanes 310 are open and two of the main vanes 310 havea second vane angle that is equal to ninety degrees such that the twomain vanes 310 are closed, thereby forming a combined main vane 1700which includes three of the main vanes 310. Rather than referring to themain vanes 310 as having forty five degree vane angles, the main mixer309 may simply be referred to as having three main vanes 310 and onecombined main vane 1700.

FIG. 18A illustrates the combined main vane 1700 in one embodiment. Thecombined main vane 1700 may be formed in a variety of manners. Invarious embodiments, the combined main vane 1700 is formed from a largemain vane 310 which is folded flat (e.g., to ninety degrees, etc.). Inthese embodiments, the large main vane 310 may be twice the size of theother main vanes 310. In other embodiments, the combined main vane 1700is formed from a first adjacent main vane 1800 and a second adjacentmain vane 1802. In these embodiments, the first adjacent main vane 1800and the second adjacent main vane 1802 are each folded flat and then thefirst adjacent main vane 1800 and the second adjacent main vane 1802 areeither joined directly (e.g., adjacent edges of each of the firstadjacent main vane 1800 and the second adjacent main vane 1802 areattached together, etc.) or indirectly (e.g., a spanning member isattached to each of the first adjacent main vane 1800 and the secondadjacent main vane 1802, etc.).

FIGS. 18B and 18C illustrate the combined main vane 1700 as being formedfrom the first adjacent main vane 1800, the second adjacent main vane1802, and a third adjacent main vane 1804. In these embodiments, thefirst adjacent main vane 1800, the second adjacent main vane 1802, andthe third adjacent main vane 1804 do not need to be bent flat and mayhave vane angles.

In FIG. 18B, the first adjacent main vane 1800 is coupled to a firstspanning member 1806 which is coupled to the second adjacent main vane1802. The first spanning member 1806 may be attached to the firstadjacent main vane 1800 so as to be closed and prevent the passage ofexhaust gases therebetween. Similarly, the first spanning member 1806may be attached to the second adjacent main vane 1802 so as to be closedand prevent the passage of exhaust gases therebetween. The firstadjacent main vane 1800 is also coupled to a second spanning member 1808which is coupled to the third adjacent main vane 1804. The secondspanning member 1808 may be attached to the first adjacent main vane1800 so as to be closed and prevent the passage of exhaust gasestherebetween. Similarly, the second spanning member 1808 may be attachedto the third adjacent main vane 1804 so as to be closed and prevent thepassage of exhaust gases therebetween.

In FIG. 18C, a first hole 1810 is incorporated into the first spanningmember 1806 and a second hole 1812 is incorporated into the secondspanning member 1808. The first hole 1810 and the second hole 1812 areconfigured to facilitate the passage of exhaust gases therethrough. Inthis way, the first hole 1810 and the second hole 1812 may mitigate theformation of a relatively high pressure area upstream of the main mixer309. It is understood that the combined main vane 1700 as shown anddescribed with reference to FIGS. 17-18C may be included in any of theembodiments of the multi-stage mixer 200 discussed herein.

FIG. 19 illustrates the flow of exhaust gases within the multi-stagemixer 200 and illustrates how the exhaust gases behave when encounteringthe first flow device 206. The exhaust gases upstream of the first flowdevice 206 are divided into a main flow 1900 (e.g., Venturi flow, swirlflow, etc.) and a circumvented flow 1902 (e.g., exhaust assist flow,etc.). The main flow 1900 is provided into the first flow device 206(e.g., the main flow 1900 is funneled into the Venturi body 302 by thefunneling edge 300, etc.).

In some embodiments, the circumvented flow 1902 is 5-40%, inclusive, ofthe sum of the circumvented flow 1902 and the main flow 1900 (e.g., thetotal flow, etc.). In these embodiments, the main flow 1900 is 60-95%,inclusive, of the sum of the circumvented flow 1902 and the main flow1900 (e.g., the total flow, etc.). Accordingly, where the multi-stagemixer 200 includes six auxiliary vanes 1108, each gap between adjacentauxiliary vanes 1108 receives 6-16%, inclusive, of the sum of thecircumvented flow 1902 and the main flow 1900 (e.g., the total flow,etc.). Similarly, where the multi-stage mixer 200 does not include theauxiliary mixer 1106 and includes six main vanes 310, each gap betweenadjacent main vanes 310 receives 6-16%, inclusive, of the sum of thecircumvented flow 1902 and the main flow 1900 (e.g., the total flow,etc.).

The main flow 1900 and the circumvented flow 1902 define a flow split.The flow split is a ratio of the circumvented flow 1902 to the main flow1900, represented as a percentage of the main flow 1900. The flow splitis a function of the diameter d_(v), the diameter d_(e), and thedistance h_(i). By varying the flow split, an optimization of targetmixing performance (e.g., based on a computational fluid dynamicsanalysis, etc.) of the first flow device 206, target deposit formation(e.g., a target amount of deposits formed over a target period of time,etc.), and target pressure drop (e.g., a comparison of the pressure ofthe exhaust gases upstream of the first flow device 206 and a pressureof the pressure of the exhaust gases downstream of the first flow device206, etc.), can be performed such that the first flow device 206 can betailored for a target application. In various embodiments, the flowsplit ratio is between five percent and seventy percent, inclusive. Thatis, the circumvented flow 1902 is between five percent and seventypercent, inclusive, of the main flow 1900.

The circumvented flow 1902 is not immediately provided to the first flowdevice 206 through the body inlet 1304. Instead, the circumvented flow1902 flows around the funneling edge 300 into the space between thefirst flow device 206 and the body of the multi-stage mixer 200. Thecircumvented flow 1902 is divided into a diverted flow 1904 and anisolated flow 1906. The diverted flow 1904 is mixed with the reductantprovided to the first flow device 206 through the port 216. For example,if the first flow device 206 includes the exhaust gas guide 307, then aportion of the circumvented flow 1902 enters the exhaust gas guide 307and flows from the exhaust gas guide 307 into the Venturi body 302 asthe diverted flow 1904. The diverted flow 1904 enters the first flowdevice 206 through the exhaust gas guide aperture 306. In embodimentswhere the first flow device 206 does not include the exhaust gas guide307, the circumvented flow 1902 may enter the Venturi body 302 as thediverted flow 1904 directly through the exhaust gas guide aperture 306.

The isolated flow 1906 does not enter the first flow device 206immediately and instead encounters the first support flange 304. Invarious embodiments, the first support flange 304 is sealed against themulti-stage mixer 200 and the Venturi body 302, and does not permit thepassage of the isolated flow 1906 through or around the first supportflange 304. In these embodiments, the isolated flow 1906 flows backtowards the body inlet 1304. As the isolated flow 1906 flows backtowards the body inlet 1304, a portion of the isolated flow 1906 mayenter the exhaust gas guide 307 and flow into the Venturi body 302 asthe diverted flow 1904. Other portions of the isolated flow 1906 mayflow past the exhaust gas guide 307 and enter the Venturi body 302through the body inlet 1304 as the main flow 1900. In other embodiments,the first support flange 304 includes at least one aperture permittingthe passage of the exhaust gases therethrough, thereby allowing at leasta portion of the isolated flow 1906 to bypass the body entirely. Thisportion of the isolated flow 1906 would mix with the main flow 1900downstream of the body outlet 1306 (e.g., after the main flow 1900 hascombined with the diverted flow 1904 and the reductant within theVenturi body 302, etc.).

According to the embodiment shown in FIG. 19, the main flow 1900 ispassed through the auxiliary vanes 1108, mixed with reductant and thediverted flow 1904, and then passed through the main vanes 310, throughthe shroud 1308, and out of the body outlet 1306.

As shown in FIG. 20, which illustrates a view of an upstream face of thefirst flow device 206, the first flow device 206 includes a secondsupport flange 2000 (e.g., upstream support flange, etc.). It isunderstood that the second support flange 2000 as shown and describedwith reference to FIG. 20 may be included in any of the embodiments ofthe multi-stage mixer 200 discussed herein.

The second support flange 2000 is coupled to the first flow device 206and to the multi-stage mixer 200. The second support flange 2000 isdisposed upstream of the first support flange 304. In variousembodiments, the second support flange 200 is disposed upstream of theexhaust gas guide 307. The second support flange 2000 facilitatespassage of the exhaust gases through the second support flange 2000. InFIG. 20, the first support flange 304 is hidden to facilitate viewing ofthe second support flange 2000.

The second support flange 2000 includes a plurality of second supportflange apertures 2001 (e.g., holes, passages, pathways, etc.). Thecircumvented flow 1902 traverses the second support flange 2000 throughthe second support flange apertures 2001. Additionally, the isolatedflow 1906 may, after being redirected upstream by the first supportflange 304, traverse the second support flange 2000 through the secondsupport flange apertures 2001, and enter the Venturi body 302 throughthe body inlet 1304. In various embodiments, the second support flange2000 may include one, two, three, four, five, six, or more secondsupport flange apertures 2001.

Each of the second support flange apertures 2001 is separated from anadjacent one of the second support flange apertures 2001 by a secondsupport flange connector 2002 (e.g., arm, rod, etc.). The second supportflange connector 2002 is integrated with the second support flange 2000and is coupled to the multi-stage mixer 200 and to the first flow device206. In one example, the second support flange connector 2002 is coupledto the Venturi body 302 while the first support flange 304 is coupled tothe shroud 1308. In some embodiments, the second support flange 2000 iscoupled to the funneling edge 300 (e.g., the funneling edge 300 is apart of the second support flange 2000, etc.).

The second support flange 2000 does not protrude into the body inlet1304 (e.g., the second support flange 2000 defines an aperturecontiguous with the Venturi body 302 and having a diameter equal to thediameter d_(v), etc.). In various embodiments, the second support flange2000 includes one, two, three, four, five, six, or more second supportflange connectors 2002. In some embodiments, the number of secondsupport flange apertures 2001 is equal to the number of second supportflange connectors 2002.

FIG. 21 illustrates a third support flange 2100 (e.g., upstream supportflange, etc.) according to an example embodiment. It is understood thatthe third support flange 2100 as shown and described with reference toFIG. 21 may be included in any of the embodiments of the multi-stagemixer 200 discussed herein.

The third support flange 2100 functions as the second support flange2000 already described. In various embodiments, the first flow device206 includes the third support flange 2100 or the second support flange2000. In some embodiments, the first flow device 206 includes both thesecond support flange 2000 and the third support flange 2100.

The third support flange 2100 may be coupled to the Venturi body 302upstream of the exhaust gas guide aperture 306, as shown in FIG. 21,which illustrates a view of an upstream face of the first flow device206. The third support flange 2100 may also be coupled to the Venturibody 302 downstream of the exhaust gas guide aperture 306 but upstreamof the first support flange 304. The third support flange 2100 may alsobe coupled to the Venturi body 302 upstream of the exhaust gas guideaperture 306. In some embodiments, the third support flange 2100 iscontiguous with the funneling edge 300 (e.g., the funneling edge 300 isa part of the third support flange 2100, etc.).

The third support flange 2100 includes a plurality of third supportflange apertures 2102 (e.g., holes, passages, pathways, etc.). Thecircumvented flow 1902 traverses the third support flange 2100 throughthe third support flange apertures 2102. In various embodiments, thethird support flange 2100 may include one, two, three, four, five, six,or more third support flange apertures 2102.

Each of the third support flange apertures 2102 is separated from anadjacent one of the third support flange apertures 2102 by a thirdsupport flange connector 2104 (e.g., arm, rod, etc.). The third supportflange connector 2104 is integrated with the third support flange 2100and is coupled to the multi-stage mixer 200 and to the first flow device206. In one example, the third support flange connector 2104 is coupledto the Venturi body 302 while the first support flange 304 is coupled tothe shroud 1308. In some embodiments, the third support flange 2100 iscoupled to the funneling edge 300 (e.g., the funneling edge 300 is apart of the third support flange 2100, etc.).

The third support flange 2100 does not protrude into the body inlet 1304(e.g., the third support flange 2100 defines an aperture contiguous withthe Venturi body 302 and having a diameter equal to the diameter d_(v),etc.). In various embodiments, the third support flange 2100 includesone, two, three, four, five, six, or more third support flangeconnectors 2104. In some embodiments, the number of third support flangeapertures 2102 is equal to the number of third support flange connectors2104.

FIGS. 22A and 22B illustrate a conduit straight vane mixer 2200according to an example embodiment. It is understood that the conduitstraight vane mixer 2200 as shown and described with reference to FIGS.22A and 22B may be included in any of the embodiments of the multi-stagemixer 200 discussed herein.

The conduit straight vane mixer 2200 includes a plurality of conduitstraight vanes 2202 each coupled to and conforming with a conduitstraight vane central hub 2206. Rather than forming apertures betweenany of the conduit straight vanes 2202, as are formed between adjacentmain vanes 310, any of the conduit straight vanes 2202 and any combinedconduit straight vanes form conduits therebetween. As explained herein,a conduit is a closed pathway with a single inlet and a single outlet(e.g., is bounded on four out of six sides, etc.).

While not shown, tips (e.g., outermost edges, etc.) of each of theconduit straight vanes 2202 is coupled to and conforms with the shroud1308 or Venturi body 302. The trailing edge of one of the conduitstraight vanes 2202 or combined conduit straight vanes extends beyondthe leading edge of an adjacent one of the conduit straight vanes 2202or combined conduit straight vanes in a streamwise direction S_(t) andthereby confines a flow of exhaust gases in a spanwise direction S_(p).The streamwise direction S_(t) is tangential to a tip of the leadingedge while the spanwise S_(p) is normal to (e.g., orthogonal to, etc.)the streamwise direction S_(t). This spanwise confinement combined withthe conforming coupling of the conduit straight vanes 2202 to theconduit straight vane central hub 2206 and to the shroud 1308 (both ofwhich confine flow in wall normal directions) create a conduit for eachof the conduit straight vanes 2202. Each conduit has four sides: a firstdefined by one conduit straight vane 2202 or combined conduit straightvane, a second defined by the conduit straight vane central hub 2206, athird defined by the shroud 1308 or Venturi body 302, and a fourthdefined by another conduit straight vane 2202 or combined conduitstraight vane. Each conduit efficiently directs the exhaust gases. Invarious embodiments, the conduit straight vane mixer 2200 is utilized inthe first flow device 206 in place of the main mixer 309. In otherembodiments, the conduit straight vanes 2202 are not coupled to theshroud 1308 and instead are coupled to and conform with the Venturi body302. In these embodiments, the conduit straight vanes 2202 are insteadcoupled to and conform with the Venturi body 302. In such embodiments,the conduit straight vane mixer 2200 may be utilized in place of or inaddition to the auxiliary mixer 1106.

In some embodiments, the conduit straight vane mixer 2200 includes two,three, four, five, six, seven, eight, or more conduit straight vanes2202. Like the main vanes 310, each of the conduit straight vanes 2202is defined by a blade angle. These blade angles may be varied such thata combined conduit straight vane (not shown) may be formed as describedwith regard to the combined main vane 1700 above. In some embodiments,the conduit straight vane mixer 2200 includes one, two, three or more ofthe combined conduit vanes. In other embodiments, the conduit straightvane mixer 2200 does not include the combined conduit vane. In anexample embodiment, the conduit straight vane mixer 2200 includes threeof the conduit straight vanes 2202 and one combined conduit straightvane.

The conduit straight vane central hub 2206 may be centered on, or offsetfrom, the mixer center axis 1302. For example, the conduit straight vanecentral hub 2206 may be centered on the body center axis 1300, andtherefore offset the radial offset h_(r) from the mixer center axis1302. The conduit straight vanes 2202 and/or the combined conduitstraight vane may be arranged symmetrically or asymmetrically about theconduit straight vane central hub 2206.

Each of the conduit straight vanes 2202 and combined conduit straightvane extend over an adjacent conduit straight vane 2202 or combinedconduit straight vane. This distance is shown in FIG. 22A as extensiondistance E_(SW). The extension distance E_(SW) is expressed as apercentage of the width in the streamwise direction S_(t) of a singleconduit straight vane 2202 at a given distance from the axis (e.g., thebody center axis 1300, the mixer center axis 1302, etc.) upon which theconduit straight vane central hub 2206 is centered. In variousembodiments, this extension distance E_(SW) is between 0% and 75%,inclusive, of the width in the streamwise direction S_(t) of a singleconduit straight vane 2202 at a given distance from the axis upon whichthe conduit straight vane central hub 2206 is centered.

The conduit straight vane mixer 2200 provides relatively high swirlvelocities even at lower blade angles for each of the conduit straightvanes 2202, thereby providing enhanced mixing of reductant with a lowerpressure drop. Another benefit of the high swirl velocities provided bythe conduit straight vanes 2202 and the combined conduit straight vaneis that high swirl velocities mitigate accumulation of depositsdownstream of the conduit straight vane mixer 2200 (e.g., along theVenturi body 302, along the shroud 1308, etc.).

Each of the conduit straight vanes 2202 and the combined conduitstraight vane is defined by a streamwise angle α_(sa) relative to anaxis upon which the conduit straight vane central hub 2206 is centered(e.g., the body center axis 1300, the mixer center axis 1302, etc.). Invarious embodiments, the streamwise angle α_(sa) is between thirtydegrees and ninety degrees, inclusive. The streamwise angle α_(sa) foreach of the conduit straight vanes 2202 and the combined conduitstraight vanes may be selected such that the first flow device 206 istailored for a target application.

The streamwise angle α_(sa) and the streamwise extension distance E_(SW)may be different for each of the conduit straight vanes 2202 and/or thecombined conduit straight vanes. Selection of streamwise angle α_(sa)and streamwise extension distance E_(SW) for each of the conduitstraight vanes 2202 and/or the combined conduit straight vanes may bemade so as to create asymmetric swirl of the exhaust gases, to directflow of the exhaust gases (e.g., towards a target location in themulti-stage mixer 200, etc.), to more uniformly distribute reductantwithin the exhaust gases, and/or to reduce deposits within the firstflow device 206 (e.g., on the Venturi body 302, etc.) and/or themulti-stage mixer 200.

The conduit straight vanes 2202 and/or the combined conduit straightvanes may be constructed using casting (e.g., investment casting, lostfoam casting, sand casting, etc.) and/or 3D printing. For example, theconduit straight vane mixer 2200 may be printed using a 3D printer byusing a file which specifies the number of the conduit straight vanes2202, the number of the combined conduit straight vanes, the streamlineangle α_(sa) for each of the conduit straight vanes 2202 and combinedconduit straight vanes, and the streamwise extension E_(SW) for each ofthe conduit straight vanes 2202 and combined conduit straight vanes.

FIG. 23 illustrates a curved vane mixer 2300 according to an exampleembodiment. It is understood that the curved vane mixer 2300 as shownand described with reference to FIG. 23 may be included in any of theembodiments of the multi-stage mixer 200 discussed herein.

In various embodiments, the curved vane mixer 2300 is utilized in thefirst flow device 206 in place of the auxiliary mixer 1106 or in placeof the main mixer 309. However, the curved vane mixer 2300 mayadditionally or alternatively be utilized in other flow devices (e.g.,the second flow device 208, the third flow device 210, the fourth flowdevice 212, etc.).

The curved vane mixer 2300 includes a plurality of curved vanes 2302 anda combined curved vane 2304. In some embodiments, the curved vane mixer2300 includes two, three, four, five, six, seven, eight, or more of thecurved vanes 2302. In some embodiments, the curved vane mixer 2300includes one, two, three or more of the combined curved vanes 2304. Inother embodiments, the curved vane mixer 2300 does not include thecombined curved vane 2304. In an example embodiment, the curved vanemixer 2300 includes three of the curved vanes 2302 and one combinedcurved vane 2304.

Each of the curved vanes 2302 and the combined curved vane 2304 isattached to a curved vane central hub 2306 that is centered about thecenter axis of the multi-stage mixer 200. The curved vanes 2302 and/orthe combined curved vane 2304 may be arranged symmetrically orasymmetrically about the curved vane central hub 2306. Like the conduitstraight vanes 2202, each of the curved vanes 2302 and the combinedcurved vane 2304 may overlap. Each of the curved vanes 2302 and thecombined curved vane 2304 extend over an adjacent curved vane 2302 orcombined curved vane 2304 the extension distance E_(SW) describedherein.

The curved vanes 2302 and the combined curved vane 2304 have a curved oraerodynamic shape which reduces pressure drop of the exhaust gases andfacilitates more even distribution of the flow downstream of the curvedvane mixer 2300, such as along a center axis of the curved vane mixer2300.

Each of the curved vanes 2302 is defined by a curved vane angle α_(cv)relative to a curved vane central hub center axis of the curved vanecentral hub 2306. Similarly, the combined curved vane 2304 may bedefined by the curved vane angle α_(cv) relative to a curved vanecentral hub center axis of the curved vane central hub 2306. Due to thecurved nature of the curved vanes 2302 and the combined curved vane2304, the curved vane angle α_(cv) is variable. The curved vane angleα_(cv) for each of the curved vanes 2302 and combined curved vanes 2304may be different from the curved vane angle α_(cv) for the others of thecurved vanes 2302 and the others of the combined curved vanes 2304.

The curved vanes 2302 and/or the combined curved vane 2304 may beconstructed using casting and/or 3D printing. For example, the curvedvane mixer 2300 may be printed using a 3D printer by using a file whichspecifies the number of the curved vanes 2302, the number of thecombined curved vanes 2304, and the curved vane angle α_(cv) for each ofthe curved vanes 2302 and the combined curved vanes 2304. In variousembodiments, the curved vanes 2302 and/or the combined curved vane 2304can be design to keep a tangential angle constant at each point alongthe curved vane 2302 or combined curved vane 2304, or to minimize anaerodynamic drag force on each curved vane 2302 or combined curved vane2304. In one embodiment, 3D printed or cast curved vanes 2303 may beinserted into the Venturi body 302 and welded to the first supportflange 304.

FIG. 24 illustrates a cross-sectional view of the curved vane mixer2300. The curved vane angle α_(cv) at a first location proximate thecurved vane central hub 2306 relative to a hub center axis of the curvedvane central hub 2306 is shown as angle α_(cv1) and the curved vaneangle α_(cv) at a second location proximate a terminal edge of thecurved vane 2302 relative to the hub center axis of the curved vanecentral hub 2306 is shown as angle α_(cv2). The angle α_(cv1) isdifferent from (e.g., smaller than, etc.) the angle α_(cv2). Aneffective curved vane angle α_(cve) relative to the hub center axis ofthe curved vane central hub 2306 is calculated based on the curved vaneangle α_(cv) along the curved vane 2302 (e.g., the angle α_(cv1), theangle α_(cv2), etc.). By using a smaller curved vane angle α_(cv) nearthe curved vane central hub 2306, pressure drop of the exhaust gases andthe probability of deposit formation are reduced. Similarly, by using alarger curved vane angle α_(cv), the swirl of the exhaust gasesdownstream of the curved vane mixer 2300 is increased. In this way, thecurved vanes 2302 and/or the combined curved vane 2304 can be optimizedto produce a swirl flow that balances a target pressure drop with atarget uniformity index.

FIGS. 25 and 26 illustrate a common central hub 2500. It is understoodthat the common central hub 2500 as shown and described with referenceto FIGS. 25 and 26 may be included in any of the embodiments of themulti-stage mixer 200 discussed herein.

The common central hub 2500 may be implemented as any of the othercentral hubs described herein (e.g., the main vane central hub 313, theauxiliary vane central hub 1109, the conduit straight vane central hub2206, the curved vane central hub 2306, etc.). The common central hub2500 is defined by a diameter d_(gch) and a length l_(gch). In variousembodiments, the diameter d_(gch) is selected such that

0.05d _(v) ≤d _(gch)≤0.5d _(v)  (21)

and the length l_(gch) is selected such that

0.02d _(v) ≤l _(gch)≤0.5d _(v)  (22)

The common central hub 2500 includes a cylindrical portion 2502 and aconical portion 2504. By incorporating the conical portion 2504, thecommon central hub 2500 may facilitate a reduction in pressure drop ofthe exhaust gases by allowing additional flow to flow towards the coreof the swirl flow (e.g., downstream of the common central hub 2500,etc.). The conical portion 2504 is defined by a cone angle. In variousembodiments, the cone angle is between ten degrees and fifty degrees,inclusive. In various embodiments, the common central hub 2500 isconical or another similar aerodynamic shape.

In various embodiments, the common central hub 2500 includes a pluralityof grooves 2506. The grooves 2506 are recessions (e.g., grooves, cuts,channels, engravings, etc.) in the common central hub 2500. In anexample embodiment, the grooves 2506 are contained within thecylindrical portion 2502 and do not extend onto the conical portion2504. In other embodiments, the grooves are not contained within thecylindrical portion 2502 and are located on the conical portion 2504.

Each of the grooves 2506 receives a common vane 2600. The grooves 2506receive a common vane 2600 in a conforming manner such that a flow ofexhaust gases follows the geometry of the common vane 2600, therebymitigating leakage of the exhaust gases between the common central hub2500 and the common vane 2600 and providing a relatively high degree ofstructural durability.

The common vane 2600 may be implemented as any of the other vanesdescribed herein (e.g., the main vanes 310, the complementary vanes1100, the auxiliary vanes 1108, the conduit straight vanes 2202, thecombined conduit straight vane, the curved vanes 2302, the combinedcurved vane 2304, etc.), and any of the other vanes described herein.Each of the common vanes 2600 may be attached to the common central hub2500 within the grooves 2506. For example, the common vanes 2600 may bewelded to the grooves 2506.

The grooves 2506 enable quicker and more consistent manufacturing of themulti-stage mixer device 200. Specifically, locating the common vanes2600 in the grooves 2506 and then attaching the common vanes 2600 to thegrooves 2506 is much easier (e.g., because such control can beimplemented via precise tooling, etc.) for a manufacturer to controlthan would be possible without the grooves 2506. Furthermore, thegrooves 2506 may facilitate low cost or rapid manufacturing techniques,such as laser welding, for coupling the common vanes 2600 to the commoncentral hub 2500.

FIG. 27 illustrates a first perforated support flange 2700. It isunderstood that the first perforated support flange 2700 as shown anddescribed with reference to FIG. 27 may be included in any of theembodiments of the multi-stage mixer 200 discussed herein.

In various embodiments, the first perforated support flange 2700 isutilized in the first flow device 206 in place of the first supportflange 304. However, the first perforated support flange 2700 mayadditionally or alternatively be utilized in other flow devices (e.g.,the second flow device 208, the third flow device 210, the fourth flowdevice 212, etc.). Unlike the first support flange 304, the firstperforated support flange 2700 is configured to facilitate the passageof exhaust gases through the first perforated support flange 2700,thereby facilitating the bypass of some of the exhaust gases around theVenturi body 302.

The first perforated support flange 2700 is illustrated in FIG. 27 inplace of the first support flange 304. Accordingly, the first perforatedsupport flange 2700 is coupled to the Venturi body 302 proximate themain mixer 309. The first perforated support flange 2700 includes atleast one of a first perforation 2702 (e.g., aperture, hole, etc.). Eachfirst perforation 2702 extends through first perforated support flange2700 such that exhaust gases may pass through the first perforatedsupport flange 2700 via the first perforation 2702.

The first perforation 2702 functions to reduce pressure drop of theexhaust gases and facilitate more even distribution of the flowdownstream of the main mixer 309, such as along a center axis of themain mixer 309. The first perforation 2702 also functions to create arelatively high shear of the exhaust gases on the body of themulti-stage mixer 200 such that accumulation of deposits near themulti-stage mixer outlet 204 of the multi-stage mixer 200 is mitigated.

In various embodiments, the first perforated support flange 2700includes between one and twenty-five, inclusive, of the firstperforations 2702. The first perforation 2702 may be circular, square,hexagonal, pentagonal, or otherwise similarly shaped. In variousembodiments, each of the first perforations 2702 has a diameter ofbetween 0.1 inches to 1 inch, inclusive.

The first perforation 2702 is disposed on a lower periphery 2704 of thefirst perforated support flange 2700. The lower periphery 2704 may be aregion of the first perforated support flange 2700 which is below themain mixer 309 (e.g., relative to the port 216, etc.). However, thefirst perforations 2702 may additionally or alternatively be located onother regions of the first perforated support flange 2700 such as a topperiphery above the main mixer 309 or a side periphery to one side ofthe main mixer 309. In various embodiments, the first perforations 2702are aligned in a concentric arc about the main mixer 309 (e.g., suchthat each of the first perforations 2702 are equally spaced from themulti-stage mixer 200, etc.).

By varying size (e.g., diameter, etc.), the location, and the number ofthe first perforations 2702, an optimization of target mixingperformance (e.g., based on a computational fluid dynamics analysis,etc.) of the first flow device 206, target deposit formation (e.g., atarget amount of deposits formed over a target period of time, etc.),target uniformity index, and target pressure drop (e.g., a comparison ofthe pressure of the exhaust gases upstream of the first flow device 206and a pressure of the pressure of the exhaust gases downstream of thefirst flow device 206, etc.), can be performed such that the first flowdevice 206 can be tailored for a target application.

FIG. 28 illustrates a second perforated support flange 2800. It isunderstood that the second perforated support flange 2800 as shown anddescribed with reference to FIG. 28 may be included in any of theembodiments of the multi-stage mixer 200 discussed herein.

In various embodiments, the second perforated support flange 2800 isutilized in the first flow device 206 in place of the first supportflange 304. However, the second perforated support flange 2800 mayadditionally or alternatively be utilized in other flow devices (e.g.,the second flow device 208, the third flow device 210, the fourth flowdevice 212, etc.).

The second perforated support flange 2800 is illustrated in FIG. 28 inplace of the first support flange 304. Accordingly, the secondperforated support flange 2800 is coupled to the Venturi body 302proximate the main mixer 309. The second perforated support flange 2800includes at least one of a second perforation 2802 (e.g., aperture,hole, etc.). Each second perforation 2802 extends through secondperforated support flange 2800 such that exhaust gases may pass throughthe second perforated support flange 2800 via the second perforation2802.

The second perforation 2802 functions to reduce pressure drop of theexhaust gases and facilitate more even distribution of the flowdownstream of the main mixer 309, such as along a center axis of themain mixer 309. The second perforation 2802 also functions to create arelatively high shear of the exhaust gases on the Venturi body 302 suchthat accumulation of deposits on the Venturi body 302 is mitigated inareas where shear force and swirl could otherwise lead to depositformation. Additionally, the location of the second perforation 2802proximate the Venturi body 302 causes the Venturi body 302 to receiveadditional heat from the exhaust gases.

In various embodiments, the second perforated support flange 2800includes between one and twenty-five, inclusive, of the secondperforations 2802. The second perforation 2802 may be circular, square,hexagonal, pentagonal, or otherwise similarly shaped. In variousembodiments, each of the second perforations 2802 has a diameter ofbetween 0.1 inches to 1 inch, inclusive. At least some (e.g., all, etc.)of the second perforations 2802 may be formed via a punching operation.This punching operation provides each of the second perforations 2802with a contoured inlet and a flared outlet. While not shown in FIG. 28,each of the second perforations 2802 may include a flap, similar to thesixth flow device vane 908.

The second perforation 2802 is disposed on an edge periphery 2804 of thesecond perforated support flange 2800. The edge periphery 2804 may be aregion of the second perforated support flange 2800 which is to the sideof the main mixer 309 (e.g., relative to the port 216, etc.). However,the second perforations 2802 may additionally or alternatively belocated on other regions of the second perforated support flange 2800such as a top periphery above the main mixer 309 or a bottom peripheryto below the main mixer 309. In various embodiments, the secondperforations 2802 are aligned in a concentric arc about the main mixer309 (e.g., such that each of the second perforations 2802 are equallyspaced from the multi-stage mixer 200, etc.).

By varying the location, size (e.g., diameter, etc.) and the number ofthe second perforations 2802, an optimization of target mixingperformance (e.g., based on a computational fluid dynamics analysis,etc.) of the first flow device 206, target deposit formation (e.g., atarget amount of deposits formed over a target period of time, etc.),target uniformity index, and target pressure drop (e.g., a comparison ofthe pressure of the exhaust gases upstream of the first flow device 206and a pressure of the pressure of the exhaust gases downstream of thefirst flow device 206, etc.), can be performed such that the first flowdevice 206 can be tailored for a target application. In variousembodiments, the open area of all of the second perforations 2802 is

$\begin{matrix}{A_{perf} = {\frac{\pi}{4}n_{perf}d_{perf}^{2}}} & (23)\end{matrix}$

where n_(perf) is the number of the second perforations 2802 andd_(perf) is the diameter of each of the second perforations 2802. Therelationship between A_(perf) and pressure drop, and the relationshipbetween A_(perf) and uniformity index, are shown in FIG. 29, whereA_(tot) is the total area of the second perforated support flange 2800.

FIG. 30 illustrates a third perforated support flange 3000. It isunderstood that the third perforated support flange 3000 as shown anddescribed with reference to FIG. 28 may be included in any of theembodiments of the multi-stage mixer 200 discussed herein.

The third perforated support flange 3000 is similar to the secondperforated support flange 2800 described herein. In various embodiments,the third perforated support flange 3000 is utilized in the first flowdevice 206 in place of the first support flange 304. However, the thirdperforated support flange 3000 may additionally or alternatively beutilized in other flow devices (e.g., the second flow device 208, thethird flow device 210, the fourth flow device 212, etc.). Unlike thefirst support flange 304, the third perforated support flange 3000 isconfigured to facilitate the passage of exhaust gases through the thirdperforated support flange 3000, thereby facilitating the bypass of someof the exhaust gases around the Venturi body 302.

The third perforated support flange 3000 is illustrated in FIG. 30 inplace of the first support flange 304. Accordingly, the third perforatedsupport flange 3000 is coupled to the Venturi body 302 proximate themain mixer 309. The third perforated support flange 3000 includes atleast one of a third perforation 3002 (e.g., aperture, hole, etc.). Eachthird perforation 3002 extends through third perforated support flange3000 such that exhaust gases may pass through the third perforatedsupport flange 3000 via the second perforation 2802. The aforementioneddescription of the second perforations 2802 similarly applies to thethird perforations 3002 and the first perforations 2702. In variousembodiments, the third perforations 3002 are equally spaced across anarc spanning from sixty degrees to three-hundred degrees relative to acenter axis of the first flow device 206 and/or the multistage mixer200.

FIGS. 31 and 32 illustrate a shrouded vane mixer 3100 according to anexample embodiment. It is understood that the shrouded vane mixer 3100as shown and described with reference to FIGS. 31-33 may be included inany of the embodiments of the multi-stage mixer 200 discussed herein.

FIG. 31 is a cross-sectional view of the shrouded vane mixer 3100. Invarious embodiments, the shrouded vane mixer 3100 is utilized in thefirst flow device 206 in place of the auxiliary mixer 1106 or in placeof the main mixer 309. However, the shrouded vane mixer 3100 mayadditionally or alternatively be utilized in other flow devices (e.g.,the second flow device 208, the third flow device 210, the fourth flowdevice 212, etc.).

The shrouded vane mixer 3100 includes a plurality of shrouded vanes 3102and a combined shrouded vane 3104. In some embodiments, the shroudedvane mixer 3100 includes two, three, four, five, six, seven, eight, ormore of the shrouded vanes 3102. In some embodiments, the shrouded vanemixer 3100 includes one, two, three or more of the combined shroudedvanes 3104. In other embodiments, the shrouded vane mixer 3100 does notinclude the combined shrouded vane 3104. In an example embodiment, theshrouded vane mixer 3100 includes three of the shrouded vanes 3102 andone combined shrouded vane 3104.

Each of the shrouded vanes 3102 and the combined shrouded vane 3104 isattached to a shrouded vane central hub 3106 that is centered about thecenter axis of the multi-stage mixer 200. The shrouded vanes 3102 and/orthe combined shrouded vane 3104 may be arranged symmetrically orasymmetrically about the shrouded vane central hub 3106. Like theconduit straight vanes 2202, each of the shrouded vanes 3102 and thecombined shrouded vane 3104 may overlap.

The shrouded vane mixer 3100 includes a recess 2908. The recess 2908 isconfigured to fit around the exhaust gas guide aperture 306 when theshrouded vane mixer 3100 is installed in the multi-stage mixer 200.

The shrouded vane mixer 3100 combines the functions of a mixer (e.g.,the auxiliary mixer 1106, the main mixer 309, etc.) with the functionsof a shroud (e.g., the shroud 1308, etc.) in a single component. In thisway, the shrouded vane mixer 3100 may reduce the cost (e.g.,manufacturing cost, etc.) and manufacturing complexity of themulti-stage mixer 200. Additionally, combining the mixer and the shroudin a single component, the shrouded vane mixer 3100, reducesmanufacturing tolerances on vane angles of the shrouded vanes 3102,thereby reducing variability between different shrouded vane mixers3100. The thickness of each of the shrouded vanes 3102 may be constantor variable throughout the shrouded vane 3102, such as vertically alongthe shrouded vane 3102 or horizontally along the shrouded vane 3102. Invarious embodiments, the shrouded vane 3102 has a thickness of between1.5 mm and 6 mm, inclusive. Similarly, in various embodiments, the edgesof each of the shrouded vanes 3102 has a radius of between 0.5 mm and 3mm, inclusive. This radius may reduce flow separation of the exhaustgases, mitigate accumulation of reductant deposits, and reduce stressconcentrations on the shrouded vanes 3102 and/or the shroud 1318.

FIG. 33 illustrates the shrouded vane mixer 3100 installed in themulti-stage mixer device 200 according to an example embodiment. In thisembodiment, the shrouded vane central hub 3106 is centered on the bodycenter axis 1300, and the body center axis 1300 is offset an angle βfrom the mixer center axis 1302. As shown in FIG. 33, the angle β is apositive angle such that the shrouded vane mixer 3100 is tilted upwardswithin the multi-stage mixer 200. In various embodiments, the angle β isbetween zero degrees and fifteen degrees, inclusive. In otherembodiments, the angle β is negative such that the shrouded vane mixer3100 is tilted downwards within the multi-stage mixer 200. In theseembodiments, the angle β may be between zero degrees and negativefifteen degrees, inclusive. In still other embodiments, the shroudedvane mixer 3100 may be tilted to either side, or some combination of theaforementioned directions.

IV. CONSTRUCTION OF EXAMPLE EMBODIMENTS

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of what may beclaimed but rather as descriptions of features specific to particularimplementations. Certain features described in this specification in thecontext of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresdescribed in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described as actingin certain combinations and even initially claimed as such, one or morefeatures from a claimed combination can, in some cases, be excised fromthe combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

As utilized herein, the terms “substantially,” “approximately,” andsimilar terms are intended to have a broad meaning in harmony with thecommon and accepted usage by those of ordinary skill in the art to whichthe subject matter of this disclosure pertains. It should be understoodby those of skill in the art who review this disclosure that these termsare intended to allow a description of certain features described andclaimed without restricting the scope of these features to the precisenumerical ranges provided. Accordingly, these terms should beinterpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

The terms “coupled,” “connected,” and the like, as used herein, mean thejoining of two components directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two components orthe two components and any additional intermediate components beingintegrally formed as a single unitary body with one another, with thetwo components, or with the two components and any additionalintermediate components being attached to one another.

The terms “fluidly coupled,” “in fluid communication,” and the like, asused herein, mean the two components or objects have a pathway formedbetween the two components or objects in which a fluid, such as exhaust,water, air, gaseous reductant, gaseous ammonia, etc., may flow, eitherwith or without intervening components or objects. Examples of fluidcouplings or configurations for enabling fluid communication may includepiping, channels, or any other suitable components for enabling the flowof a fluid from one component or object to another. As described herein,“preventing” should be interpreted as potentially allowing for deminimus circumvention (e.g., less than 1%) of the exhaust gases.

It is important to note that the construction and arrangement of thesystem shown in the various example implementations is illustrative onlyand not restrictive in character. All changes and modifications thatcome within the spirit and/or scope of the described implementations aredesired to be protected. It should be understood that some features maynot be necessary, and implementations lacking the various features maybe contemplated as within the scope of the application, the scope beingdefined by the claims that follow. When the language “a portion” isused, the item can include a portion and/or the entire item unlessspecifically stated to the contrary.

1. A multi-stage mixer, comprising: a multi-stage mixer inlet configuredto receive exhaust gas, the multi-stage mixer inlet centered on a firstaxis; a multi-stage mixer outlet configured to provide the exhaust gasto a catalyst, the multi-stage mixer outlet centered on the first axis;a first flow device configured to receive the exhaust gas from themulti-stage mixer inlet and to receive reductant such that the reductantis partially mixed with the exhaust gas within the first flow device,the first flow device comprising: a plurality of main vanes; and aplurality of main vane apertures interspaced between the plurality ofmain vanes, the plurality of main vane apertures being configured toreceive the exhaust gas and to cooperate with the plurality of mainvanes to provide the exhaust gas from the first flow device with a swirlflow that facilitates mixing of the reductant and the exhaust gas; and asecond flow device configured to receive the exhaust gas and thereductant from the first flow device, the second flow device comprisinga plurality of second flow device apertures configured to provide theexhaust gas and the reductant from the second flow device to thecatalyst via the multi-stage mixer outlet.
 2. The multi-stage mixer ofclaim 1, wherein: the plurality of main vane apertures collectivelydefine a first open area; wherein the plurality of second flow deviceapertures collectively define a second open area; and wherein the firstopen area is equal to the second open area.
 3. The multi-stage mixer ofclaim 1, further comprising an exhaust gas guide coupled to the firstflow device, the exhaust gas guide configured to receive the exhaust gasfrom the multi-stage mixer inlet and configured to cause the exhaust gasto contact the reductant such that the reductant is propelled into thefirst flow device by the exhaust gas.
 4. The multi-stage mixer of claim1, wherein the first flow device further comprises: a body inlet havinga first diameter; a body outlet having a second diameter less than thefirst diameter; and a frustoconical shroud contiguous with the bodyoutlet.
 5. The multi-stage mixer of claim 1, wherein the first flowdevice further comprises: a plurality of auxiliary vanes; and aplurality of auxiliary vane apertures interspaced between the pluralityof auxiliary vanes, the plurality of auxiliary vane apertures configuredto receive the exhaust gas and cooperate with the plurality of auxiliaryvanes to provide the exhaust gas into the first flow device with a swirlflow that facilitates mixing of the reductant and the exhaust gas. 6.The multi-stage mixer of claim 5, wherein the swirl flow iscounter-swirl flow.
 7. The multi-stage mixer of claim 5, wherein theswirl flow is co-swirl flow.
 8. The multi-stage mixer of claim 5,wherein: the first flow device further comprises: a body inlet; and abody outlet; and the plurality of auxiliary vanes is located proximatethe body inlet and the plurality of main vanes is located proximate thebody outlet.
 9. The multi-stage mixer of claim 5, wherein: themulti-stage mixer is centered on a mixer center axis; the first flowdevice is centered on a body center axis; and the body center axis isoffset from or angled relative to the mixer center axis.
 10. Themulti-stage mixer of claim 5, wherein the first flow device furthercomprises a first support flange configured to secure the first flowdevice within the multi-stage mixer, the first support flange configuredto establish a seal between the first flow device and the multi-stagemixer.
 11. The multi-stage mixer of claim 10, wherein the first flowdevice further comprises a second support flange comprising: a pluralityof second support flange apertures configured to facilitate the passageof exhaust gas therethrough; and a plurality of second support flangeconnectors configured to secure the first flow device within themulti-stage mixer.
 12. The multi-stage mixer of claim 11, wherein: thefirst flow device further comprises: a body inlet; and a body outlet;and the second support flange is located proximate the body inlet andthe first support flange is located proximate the body outlet.
 13. Themulti-stage mixer of claim 10, wherein the first flow device furthercomprises a first perforated support flange comprising a plurality offirst perforations configured to facilitate the passage of exhaust gastherethrough, the first perforated support flange configured to securethe first flow device within the multi-stage mixer.
 14. The multi-stagemixer of claim 13, wherein the first flow device further comprises asecond support flange comprising: a plurality of second support flangeapertures configured to facilitate the passage of exhaust gastherethrough; and a plurality of second support flange connectorsconfigured to secure the first flow device within the multi-stage mixer.15. The multi-stage mixer of claim 14, wherein: the first flow devicefurther comprises: a body inlet; and a body outlet; and the secondsupport flange is located proximate the body inlet and the firstperforated support flange is located proximate the body outlet.
 16. Amulti-stage mixer, comprising: a multi-stage mixer inlet configured toreceive exhaust gas; a multi-stage mixer outlet configured to providethe exhaust gas to a catalyst; and a first flow device configured toreceive the exhaust gas from the multi-stage mixer inlet and configuredto receive reductant such that the reductant is partially mixed with theexhaust gas within the first flow device, the first flow devicecomprising: a Venturi body defined by a body inlet proximate themulti-stage mixer inlet and a body outlet proximate the multi-stagemixer outlet; a plurality of main vanes positioned within the Venturibody and proximate the body outlet; a plurality of main vane aperturesinterspaced between the plurality of main vanes, the plurality of mainvane apertures configured to receive the exhaust gas and cooperate withthe plurality of main vanes to provide the exhaust gas from the firstflow device with a swirl flow that facilitates mixing of the reductantand the exhaust gas; a plurality of auxiliary vanes positioned withinthe Venturi body and proximate the body inlet; and a plurality ofauxiliary vane apertures interspaced between the plurality of auxiliaryvanes, the plurality of auxiliary vane apertures configured to receivethe exhaust gas and cooperate with the plurality of auxiliary vanes toprovide the exhaust gas into the Venturi body with a swirl flow thatfacilitates mixing of the reductant and the exhaust gas.
 17. Themulti-stage mixer of claim 16, wherein: the multi-stage mixer iscentered on a mixer center axis; the Venturi body is centered on a bodycenter axis; and the body center axis is offset from or angled relativeto the mixer center axis.
 18. The multi-stage mixer of claim 16,wherein: the Venturi body comprises a frustoconical shroud contiguouswith the body outlet; the body inlet has a first diameter; and the bodyoutlet has a second diameter less than the first diameter.
 19. Themulti-stage mixer of claim 16, wherein: the first flow device furthercomprises an exhaust gas guide coupled to the Venturi body; wherein theVenturi body comprises an exhaust gas guide aperture and the exhaust gasguide is positioned about the exhaust gas guide aperture; wherein theexhaust gas guide is configured to separately receive exhaust gas andreductant from outside of the Venturi body, mix the exhaust gas andreductant received from outside of the Venturi body in the exhaust gasguide, and provide the mixed exhaust gas and reductant into the Venturibody.
 20. A multi-stage mixer, comprising: a multi-stage mixer inletconfigured to receive exhaust gas; a multi-stage mixer outlet configuredto provide the exhaust gas to a catalyst; and a first flow deviceconfigured to receive the exhaust gas from the multi-stage mixer inletand receive reductant such that the reductant is partially mixed withthe exhaust gas within the first flow device, the first flow devicecomprising: a Venturi body defined by a body inlet proximate themulti-stage mixer inlet and a body outlet proximate the multi-stagemixer outlet and including an exhaust gas guide aperture disposed alongthe Venturi body between the body inlet and the body outlet; a pluralityof main vanes positioned within the Venturi body and proximate the bodyoutlet; a plurality of main vane apertures interspaced between theplurality of main vanes, the plurality of main vane apertures configuredto receive the exhaust gas and cooperate with the plurality of mainvanes to provide the exhaust gas from the first flow device with a swirlflow that facilitates mixing of the reductant and the exhaust gas; andan exhaust gas guide coupled to the Venturi body about the exhaust gasguide aperture, the exhaust gas guide configured to separately receiveexhaust gas and reductant from outside of the Venturi body, mix theexhaust gas and reductant received from outside of the Venturi body inthe exhaust gas guide, and provide the mixed exhaust gas and reductantinto the Venturi body.
 21. The multi-stage mixer of claim 20, wherein:the multi-stage mixer is centered on a mixer center axis; the Venturibody is centered on a body center axis; and the body center axis isoffset from or angled relative to the mixer center axis.
 22. Themulti-stage mixer of claim 20, wherein: the Venturi body comprises afrustoconical shroud contiguous with the body outlet; the body inlet hasa first diameter; and the body outlet has a second diameter less thanthe first diameter.
 23. The multi-stage mixer of claim 22, wherein theVenturi body comprises a funneling edge contiguous with the body inletand configured to funnel the exhaust gas into the body inlet.
 24. Themulti-stage mixer of claim 20, wherein: each of the plurality of mainvanes is coupled to a main vane central hub; each of the plurality ofmain vanes is defined by a main vane angle relative to a hub center axisof the main vane central hub; the main vane angle for each of theplurality of main vanes is between zero degrees and forty-five degrees,inclusive; and the main vane angle for one of the plurality of mainvanes is different from the main vane angle for another of the pluralityof main vanes.
 25. The multi-stage mixer of claim 24, wherein each ofthe plurality of main vanes is coupled to and conforms with the Venturibody.
 26. A multi-stage mixer, comprising: a multi-stage mixer inletconfigured to receive exhaust gas; a multi-stage mixer outlet configuredto provide the exhaust gas to a catalyst; and a first flow deviceconfigured to receive the exhaust gas from the multi-stage mixer inletand receive reductant such that the reductant is partially mixed withthe exhaust gas within the first flow device, the first flow devicecomprising: a Venturi body defined by a body inlet proximate themulti-stage mixer inlet and a body outlet proximate the multi-stagemixer outlet and including an exhaust gas guide aperture disposed alongthe Venturi body between the body inlet and the body outlet; a pluralityof conduit straight vanes positioned within the Venturi body andproximate the body outlet, the plurality of conduit straight vanesconfigured to interface with the exhaust gas and provide the exhaust gasfrom the first flow device with a swirl flow that facilitates mixing ofthe reductant and the exhaust gas; and an exhaust gas guide coupled tothe Venturi body about the exhaust gas guide aperture, the exhaust gasguide configured to separately receive exhaust gas and reductant fromoutside of the Venturi body, mix the exhaust gas and reductant receivedfrom outside of the Venturi body in the exhaust gas guide, and providethe mixed exhaust gas and reductant into the Venturi body.
 27. Themulti-stage mixer of claim 26, wherein: the multi-stage mixer iscentered on a mixer center axis; the Venturi body is centered on a bodycenter axis; and the body center axis is offset from or angled relativeto the mixer center axis.
 28. The multi-stage mixer of claim 26,wherein: the Venturi body comprises a frustoconical shroud contiguouswith the body outlet; the body inlet has a first diameter; and the bodyoutlet has a second diameter less than the first diameter.
 29. Themulti-stage mixer of claim 28, wherein the Venturi body comprises afunneling edge contiguous with the body inlet and configured to funnelthe exhaust gas into the body inlet.
 30. The multi-stage mixer of claim26, wherein: each of the plurality of conduit straight vanes is coupledto a conduit straight vane central hub; each of the plurality of conduitstraight vanes is defined by a streamwise angle relative to a hub centeraxis of the conduit straight vane central hub; the streamwise angle foreach of the plurality of conduit straight vanes is between thirtydegrees and ninety degrees, inclusive; and the streamwise angle for oneof the plurality of conduit straight vanes is different from thestreamwise angle for another of the plurality of conduit straight vanes.31. The multi-stage mixer of claim 26, wherein each of the plurality ofconduit straight vanes is coupled to and conforms with the Venturi bodysuch that each of the plurality of conduit straight vanes cooperateswith the Venturi body to form a conduit.
 32. The multi-stage mixer ofclaim 26, wherein: one of the plurality of conduit straight vanesextends over another of the plurality of conduit straight vanes anextension distance; the one of the plurality of conduit straight vaneshas a width in the streamwise direction; and the extension distance isbetween zero and seventy-five percent, inclusive, of the width in thestreamwise direction of the one of the plurality of conduit straightvanes.